Szamitastechnika jegyzet 1. fejezet
UNIVERSITY MEDICAL SCHOOL OF DEBRECEN
CENTRE FOR EDUCATIONAL DEVELOPMENT
UNIVERSITY HANDBOOK OF INFORMATICS
1
Dr. László AGÓCS
INTRODUCTION TO MICROCOMPUTERS
(MANUSCRIPT, UPDATED VERSION)
Table of Contents
1.1 Introduction 2
1.2 Fundamental Concepts 5
1.3 Construction and Operating System of IBM PCs 9
1.4 Norton Commander 22
1.5 Computer Networks 29
1.6 Dictionary 36
1.7 Glossary 48
1.8 The Hungarian Keyboard (Used at the DOTE) 60
1.9 The IBM Character Set 61
DEBRECEN, 1995
1.1 Introduction
Nowadays computers can be used almost in every field of our everyday life. In this so called "information age", computer means a revolution in communication. In former times we talked about "computing" or "computational technique" but nowadays we rather use the term "informatics", which indicates the changing role of computers. At the beginning people used computers mainly to compute something but now we use them mostly to store, process and retrieve information.
Computers in Everyday Life
Word processing
Computers can be used as a very intelligent typewriter. With a word processor program you can type in your text in the same way as with a typewriter but you can store it on magnetic disk, retrieve it later, correct the mistakes, change the order of the sentences, etc. Spelling checkers check the words in your document and thesaurus programs suggest alternative words. Dictionary programs give the explanatory or meaning of the words. You can freely format characters, paragraphs and divisions and make a press-ready copy on a laser printer. Desktop publishing systems are designed to format sophisticated documents as a book or a newspaper.
Database Management
Computers can store numbers in the cells of their memory. These numbers represent not only ordinary numbers but also real numbers, characters, program commands. Each cell can contain a number among 0 and 255 and this information unit is called 1 byte. 1 kilobyte=1024 bytes and 1 megabyte=1024 kilobytes. The characters are coded with numbers (e.g., A=65). On a CD-ROM (which is an ordinal compact disk and a special drive), or a hard disk drive (high capacity special magnetic media) with a storing capacity of 600 megabytes, you can store 600x1024x1024=629,145,600 characters. That equals to the text of about 600 books! You can not only store this fantastic quantity of information but you can search for data very quickly with a database management system.
Calculation
Nevertheless, computers are applicable computing and calculating things. Spreadsheet programs stores the numbers, formulas or texts in two dimensional tables. If you type in formulas (e.g., statistical functions) and change the numbers, the computer recalculates the full table. The sophisticated statistical programs (such as SPSS, BMDP) can perform a variety of complicated statistical analysis.
Computer Graphics
Representation of data in graphic format is very important when illustrating something. Spreadsheet programs include a graphic program that can draw diagrams with the data contained in the table. There are programs to make charts, freehand drawings, and to manipulate drawings or photographs loaded into the memory by scanners. The new generation of computers (the so called multimedia computers) can digitize the pictures in real time so they can store moving pictures from the video signal of cameras.
Game
Certainly, the computer is also applicable to play exciting games. These games are new computer games or simulations of real games (e.g., chess, card games, pool, football, etc.). As G. Kemeny - who is Hungarian by birth and developed the BASIC programming language in the United States - said: The games have an important role to get over the beginners' aversions to the computers.
Computers in Medicine
Patient Databases
Computers are used to store the patients' personal, data, medical history, laboratory results, etc. The pieces of information can be coded by numbers to identify the symptoms, disease and interventions, etc., precisely and up-to-date, so doctors can access information very quickly. The management of the health institutions and the social insurance system can control the costs of the treatment.
Monitoring
In an intensive care unit, computers can monitor the patients' physiological functions when connected to the monitoring equipments. In such cases, computer evaluates the circumstances and alerts the physician if it is necessary. Pace-makers, hearing aids, artificial limbs, kidney machines have all been computerized.
Laboratory systems
Most of the modern laboratory equipments contain a built in computer system to store and analyze data; the computer accesses to the data on-line without human intervention. The doctor gets only the results or they appear in the patient database immediately.
Signal and picture processing
Computer can read EKGs and by pattern matching, classify them as normal or abnormal. The computer tomography (CT) takes thousands of x-rays slices of body, then combine them into one 3D picture. Future computers will be able to analyze difficult images such as histology sections.
Expert Systems
If you collect the facts and deductive rules of a certain domain of knowledge and enter them into a logical programming system (such as LISP or PROLOG), the computer would answer your questions. Expert systems can help in decision making (e.g., to make the diagnose), dosing of medicines (e.g., in hypertension or diabetes).
Computers in Science and Research
Calculation
Computers are very efficient in processing the results of scientific experiments. You can write your article with a word processor, store the data in a spreadsheet, calculate the results and represent them with a graphic program. The so called integrated softwares (e.g., FrameWork, Symphony, Microsoft Windows) contains all of these program elements. The sophisticated statistical program packages such as SPSS or BMDP can be used to produce complicated statistical analysis.
Simulation and Modelling
A computerized model of a real object renders to experiment without any danger and high costs. A computer model consists of some initial states and formulas to predict how the state will change over time under changing circumstances. The results can be displayed in the form of numbers, texts or graphics.
Retrieving Scientific Information
It is well-known that the quantity of information is doubled in every 5 year. It is increasingly important for the researchers to get systematic information very fast. For this purpose many scientific databases are available with abstracts and even full articles. You can search for data in these databases in an associative way, with the help of a keyword system. The most powerful medical database is MEDLINE with the abstracts of more than 3,000 medical journals. It is available also on CD-ROMs.
Computers in Education
Tutorial
Computers can also store information selected with learning. A tutorial program not only presents information to the students but helps them to choose a convenient way to access it. The new storage devices give a huge mass of information to the student. A CD-ROM can store all medical textbooks with indexes and cross-references, or a computer controlled video-disk contain 54,000 pictures from human anatomy, etc.
Drill and Practice
The computer is extremely patient with the students. It is an ideal tool to practise (learn) mechanical and boring subjects, e.g., anatomy or languages.
Simulation
There are many simulation programs of real machines and processes, e.g., car driving, flight simulation, etc. These programs make one practice without a risk. In medicine students can practise the diagnose making or treatment processes without any danger. Another type of the simulation programs demonstrates the functions of the body using computer graphics.
Networking
Networking means connection of computers to each other. The simplest way to do this is to connect them through their serial or parallel ports via cable or modems (connected to the telephone network).
The local area network (LAN) of a hospital allows you to use the central patient database or achieve the decentralized database of an other ward. The laboratory machines are also connected to the system so their data appears immediately in the patient database.
An up-to-date health service of a country is unimaginable without a well-constructed computer network.
The international networks can be reached over the telephone lines (CompuServe) or via LANs. There are very important scientific networks such as EARN, BITNET, INTERNET, EDUNET. Researchers can write to each other through electronic-mail system of these networks and can use special scientific data banks, etc.
1.2 Fundamental Concepts
Short History of Computing
[pic]
The automatic loom of Jacquard
It was a very old desire to automate boring and tiring calculations. This could be realized only in the second half of 20th century, thanks to the development of electronics, industry and the military requirements.
The first mechanical calculator was prepared by LEIBNITZ based on the ideas of PASCAL. In this machine the arithmetical operations were performed by cog-wheels. However, there was a great problem with this machine. If one had to make the same calculation with other initial numbers, he had to repeat all the long procedure. To solve this problem, a new idea was raised: to store this queue of operations: the so called program. Charles BABBAGE designed the first program controlled computer. He used punch cards to store data, and external keys to set up the program. The program was written by Ada LOVELACE (the daughter of Lord Byron). They could not assemble the machine due to the poor industrial background: it was assembled in the 20th century and was proved that it could work.
The punched card was the most popular data storage medium until the recent past. It was applied by Joseph Marie JACQUARD to control his automatic loom in 1808. The technique of processing the punched cards was worked out by Herman HOLLERITH for the American administration. He established the famous IBM Company.
[pic]
John Von Neumann (Neumann János)
ENIAC was the first electronic computer (1944). It was a big monster built from relays and radio tubes. This computer was used by the US Army to calculate differential equations that determine the flight of bullets. UNIVAC (1946) was the first commercial computer.
The concept of the computer was forwarded by John NEUMANN (who was Hungarian by born):
- The computer should be used as a universal machine to solve various tasks.
- The computer should be fully electronized.
- The parts of computer:
- Central Processor Unit (CPU)
- Memory
- Input-Output Unit (I/O).
- The programs and data should be stored the same way, and inside the computer.
- Binary numbers are required to store program and data.
Evolution of computers can be classified into four generations:
1. generation: vacuum tube machines 1944-1960
2. generation: transistor machines 1960-1970
3. generation: integrated circuit machines 1970-
4. generation: LSI (Large Scale of Integration) computers, micros 1978-
Formerly, a computer could run only one program at a time, and only the operators were allowed use it. The development of time-sharing method was a major brake-through from the viewpoint of users. The high capacity computer runs many programs simultaneously, by changing between them very quickly: it seems as if these programs run at the same time. The programs or program sets, the so called jobs have a rank of priority that determines the order of their execution. A job gets the control over the CPU, when the program before it in the queue asks for such an action that does not absorb the CPU (e.g., input-output operation). That is multitasking or multiprogramming.
At the beginning, the users could not work with a time-shared computer directly. The user (programmer) prepared the program on paper and gave it to the operators. They transferred the program to punched cards or paper tape, and loaded it into the computer's memory. If any mistake occurred, the program was rejected. This was the so called batch-processing.
Later, in the multi-user systems, several terminals were connected to the mainframe computer. It made multi-access possible for the end-users. These terminals were simple electric typewriters at the beginning. The user typed in the programs or commands on the keyboard, and the computer printed its messages on paper. These terminals were followed by the cathode-ray tube (CRT) monitors.
The next break-through was the appearing of microprocessors and microcomputers in the later 70s. These cheap machines spread widely. Nowadays these computers have higher operating speed and memory capacity than the former mini- or megacomputers.
The third important step was networking. The local, metropolitan and long distance networks help us to communicate with other microcomputers, access large databases, to use high capacity mainframes, etc.
Working Concepts of Computers
The fourth generation computers are designed keeping the Neumann concepts in mind.
The units of the computer are connected to each other through data buses of 8, 16, 32 or 64 bits (wires). Each unit is attached to these lines directly, but the CPU controls the traffic.
The memory consists of cells or registers. Each memory cell represents 1 byte (8 bit). The cells have numbers, and they are called addresses. The content of a memory cell can be a command for the CPU, or a piece of data (ordinal number or character coded by this number) depending on its location.
[pic]
Schematic, logical sketch of a microcomputer
The microprocessor has few registers that are used only to store the data necessary to run a program. These registers can consist of 1, 2, 4, 8 joined bytes so we talk about 8, 16, 32 or 64 bit processors. A 16 bit processor is faster than an 8 bit one, because the 16 bit bus can transfer twice the data as a 8 bit one in a given time. However, the operating speed of the computer also depends on the width of the external buses, e.g., there are 16 bit computers with a 8 bit data bus (IBM XT), or 32 bit computers with 16 bit data bus (IBM AT). The most important register is the accumulator, that stores data and the results of operations. Microprocessors can perform only simple operations, e.g., it can load a byte to a register from the accumulator, from registers to the accumulator and vice versa. It can add, subtract and compare contents of two registers too.
As we have seen, the memory contains both the program and the data. There are several types of memory used in the microcomputers: ROM, EPROM and RAM. The ROM (Read Only Memory) contains the programs and data that are absolutely necessary for the computer to function. Its content is not changeable, and remains when the computer is turned off. EPROM (Erasable Programmable Read Only Memory) is a special version of ROM. It works the same way as a ROM, but if it is necessary, we can erase its content with UV-light. RAM (Random Access Memory) is used to store and retrieve the application programs and dynamic data of the system. "Random Access" means that all the cells can be accessed in equal time. Its content is lost when you turn off the computer.
The most important peripherals are backing stores that contain the application programs and data. We can load the programs and data from them to the RAM - and in most of the cases -, backwards. These stores are usually magnetic devices (floppy disk drives, hard disk drives) or optical stores (WORM, CD-ROM).
The other peripherals serve for the communication with the machine. We can instruct the computer, or feed data into it using input devises: keyboard, mouse, light pen, scanner. The computer sends its messages to the monitor or to the printer.
Coordinated working of the computer is ensured by the system of interrupts. The CPU can only do one operation at a time, the other units let it know their needs by sending an interrupt request. The processor ceases the execution of all program in certain time intervals and refreshes the RAM, checks the keyboard and the interrupts. Therefore, the effect of an interrupt request is not satisfied immediately. There is a priority queue of the interrupts and some of them can mask the others.
The computer's "mother language" is binary, but it is not comfortable for the programmers to use it. Instead, they use the hexadecimal (16 based) number system. In this system every byte can be written with two digits. The computer understands only the machine code programs which are queues of hexadecimal numbers. Some of these numbers are commands for the computers and others are the operands of these commands. For example,
A9 00 (in decimal form: 169 0)
instructs a 6502 processor to load a zero to the accumulator register. You can imagine how difficult to build a program with such little bricks. Assembly level programming languages are a little bit comfortable because we can use simple symbols instead of numbers ($ is the shorten form of hexadecimal):
lda $00 (LoaD to Accumulator 00).
The greatest advantage of these languages is, that the programmer can label the steps of the program and use these labels instead of the hexadecimal addresses. The assembly source code can be translated to object code by using an assembler compiler.
The high level programming languages made the programmer's life much easier with their powerful commands. But the large number of them (ALGOL, FORTRAN, COBOL, PL-1, BASIC, PASCAL, FORTH, Clipper, etc.) indicates that they are not universal.
There are two types of high level languages; the interpreter and the compiler type. The interpreter translates the program step-by-step even in the phase of program writing. So the programmer gets the error messages immediately but the running speed is very low because the interpreter translates the program every time when it runs. The compiler first translates the full source code and then runs it. So the speed is higher but the programmer has to wait for the translating. The result of compiling can be machine code or a pseudo-code. In this later case, a linker program is used to organize the machine code, with the help of a routine collection called library.
Programming is very simple when using high level languages, but execution is much slower. However, it is a hard work programming in assembly. There is an intermediate level (e.g., the C language) that mixes the advantages of these two levels. Its data structure is very close to the registers of the computers, so a C program runs very fast. It has a powerful high level command set so programming is easier than in assembly language.
The "physical" parts (mechanisms, electronic circuits) of a computer are called as hardware, in contrast to the "intellectual" part (input-output systems, operating systems, application programs, documentation, etc.), which is termed as software. We often do not know what task is served by the hardware or by the software, and this is not important at all.
Recent Developments
Nowadays the so called fourth generation programming languages are used to prescribe all the details of the resolution (the algorithm), so the problem is solved by the programmer and not by the computer. The machine "only" executes the orders of the programmer. The goal of recent developments is to make the computer capable of problem solving. This fifth generation or logical programming languages (LISP, PROLOG) can store the data and the rules of deduction, so they can answer to the users' questions.
There are two major disadvantages of the fourth generation computers. The first is, that only the numerical calculations are relatively fast, but text or image processing is very slow. These machines are not really suitable to solve such problems as "understanding" sentences, translating texts to another natural language, controlling robots, etc. The second problem is that the development and maintenance of programs are very time-consuming, and adapting a program from a machine or a programming language to an other is very difficult.
There are several attempts to solve these problems and are summarized under the development of the fifth generation computers.
One possible way is, to design and produce much more complex electronic circuits with the VLSI (Very Large Scale of Integration) technology. The second is parallel computing with using of more than one processor in the computers or connecting several computers to each other. The third is to use optical elements in the computers.
The problems of software development can be solved either using structured, modular or object-oriented programming techniques, or by using the new functional or logical programming languages such as LISP, APL or PROLOG.
1.3 Construction and Operating System of IBM PCs
History of IBM PCs
The first popular microcomputer was the APPLE II with its famous CP/M operating system in 1979. In the early 80s the microcomputers based on 8 bit microprocessors (8080, Z80, 65xx) could not satisfy the users' demands. Then, IBM (International Business Machines), the largest computer manufacturer of the world, came out with its Intel 8080 16 bit processor personal computer: the IBM PC. Its first appearance did not differ from the 8 bit home computers with 8 bit data bus, 4.77 MHz clock signal, 64 kbyte of RAM, built in BASIC interpreter in its ROM, magnetic cassette backing store, etc. Anyway, the construction of this machine made it possible to add more RAM and a floppy disk drive, too.
The next version was the IBM XT, the first computer equipped with a hard disk drive. This computer and its operating system, the MS-DOS (MicroSoft Disk Operating System) became an international standard. Its fantastic spreading origins from two sources. The first was that IBM could take maximum advantage of its well-established market and it absorbed the capacity of the software companies for a long time. The second reason was the simple and open architecture of the machine. IBM obtained the parts of its machine mainly from other firms. The processor was delivered by Intel, operating system and BASIC interpreter was developed by Microsoft, the disk drives were manufactured by Seagate and Tandon. Patent laws protected only the ROM BIOS. The computer could be built up from simple 8 bit catalogue integrated circuits, so many manufacturers (e.g., on the far east) began to produce its duplicates, the so called clones.
As we said above, the IBM XT could use hard disks (fixed disks or winchesters are synonyms). These equipments with their very short accessing time and high storage capacity (2-25 Mbyte) made its applications in business and industry possible. Then the new 8 MHz 8086 microprocessor appeared. The 8087 arithmetical co-processor made the arithmetical operations faster.
IBM AT contains the Intel 80286 microprocessor with 32 bit registers and a 16 bit data bus. The AT 386 came out in 1987 with a real 32 bit 80386 processor that has a 32 bit data bus and an advanced command set. The 386SX computer has a 386 compatible processor with a 286 bus architecture. It was followed by the 64 bit AT 486, and the high performance 486DX2 processors. This later processor is the fastest in the world in its own category. Nowadays these machines are the most popular personal computers along with an other generation of computers: the Motorola 6800 processor based computers, such as ATARI 520ST, 1040ST, Commodore Amiga, APPLE Macintosh. In 1988, IBM began to produce its new personal computer: the PS2 (Personal System 2). This series was not so successful, because of its closed architecture and relatively weak performance, in contrast an AT386 or 486. Now a new AT usually has 4-16 Mbyte RAM and 200-600 Mbyte fixed disk, with a processor made by the Intel, AMD or Cyrics. The newly developed processors (Pentium, PowerPC) have an increased speed but these machines are very expensive. In these days the 100 Mhz 486 DX4 processor has the best performance/speed ratio.
Paralell to the development of the processors, three very important operation systems came out in 1994 and 1995: the OS2 Warp and the Windows 95 for the IBM PCs and IBM PowerPCs and the new version of the Apple operating system for the Power Macintosh machines. These are completely 32 bit operating systems with real multi-tasking facilities.
Construction of IBM PCs
The processors of XTs can address 1 Mbyte of memory, the maximum size of RAM is 640 kbyte. The 80286 processor can address up to 1 Gbyte, but in most of the cases it is used as a 8086 processor with similar addressing mode. Only the 386 and 486 processors provided the economical and conformable usage of RAM above 1 Mbyte possible.[1]
The IBM PC has a modular construction. The most important part is the mother board that contains the microprocessor, ROM and RAM. There are a few (4-8) expansion slots on the mother board to hold the modular cards:
Address (hexadecimal) Size
00000 +--------------------------------------+
¦ ¦
¦ ¦
¦ Free RAM ¦
¦ (256-640 K) ¦
¦ ¦ 640 K
A0000 ¦--------------------------------------¦
¦ Screen controller ¦ 64 K
¦ ¦
¦ ¦
¦ ¦
B0000 ¦--------------------------------------¦
¦ Monochrome screen (4 K) ¦ 32 K
¦ ¦
¦ ¦
¦ ¦
B8000 ¦--------------------------------------¦
¦ Color graphic screen (16 K) ¦
¦ ¦
C0000 ¦--------------------------------------¦
¦ ROM expansions ¦
¦ ¦ 216 K
F6000 ¦--------------------------------------¦
¦ ROM BASIC ¦ 32 K
¦ ¦
¦ ¦
¦ ¦
FE000 ¦--------------------------------------¦
¦ ROM-BI0S ¦ 8 K
FFFFF +--------------------------------------+
Memory distribution of IBM PCs
- Screen controller card: contain the RAM necessary to store the screen information and the electronic circuits to produce the video or RGB signals for the monitor. There are a few popular types of it:
- Monochrome card: produces only alphanumeric characters (numbers, characters and symbols) on the screen so it is suited only to use in offices. Its screen contains 25 rows and 80 columns.
- CGA color graphic card (Color Graphics Adapter): is not only applicable in text mode (25x80 or 25x40), but in graphics mode also, where each pixel of the screen can be controlled separately. Its graphics resolution is 640x200 with two colors or 320x200 with four colors.
- Monochrome graphic card (Hercules, MGP): has a better resolution (720x348) but only in black and white.
- EGA color graphic card (Enhanced Graphics Adapter): has 640x380 resolution with 16 colors. It is compatible with the CGA adapter because it can display graphics of low resolution, too.
- VGA color graphic card (Video Graphics Array): gives the best graphics with 640x480, 800x600 (standard VGA) and 1024x768, 1280x1024 (super VGA) resolution with 256 and millions of colors.[2]
- XGA color graphic card (eXtended Graphic Array): gives the highest possible resolution (1280x1024) in 16 million colors. This type of cards is quite expensive, and are not used widely yet.
- Disk controller card: controls the floppy and hard disk drives.
- Input-output card: usually contains a serial port (RS-232 standard) and a parallel port (CENTRONICS standard). Two parallel ports (LPT1, LPT2) and two serial ports (COM1, COM2) can be used in the same time. Serial ports usually are connected to the mouse, another computer or phone modem and parallel ports to printers.
[pic]
Appearance of an IBM PC
At the beginning a standard AT had a:
- motherboard with 80286 and 1 Mbyte of RAM,
- CGA card,
- I/O card with one serial and one parallel port,
- disk controller for the floppy and hard disk drive,
- 8 expansion slots,
- 1.2 Mbyte floppy disk drive,
- 20 Mbyte hard disk drive,
- 200 W power supply unit.
Nowadays, ATs can handle 40-600 Mbyte winchesters (thank to MS-DOS 4.00 and higher versions) and 2-8 Mbyte RAM. 386SX, 386 and 486 PCs use 32-256 kbyte cache memory to make disk operations faster.
In XT's, hardware configuration can be set up by dip switches or jumpers. In ATs there is a CMOS-RAM fed with an accumulator to store the configuration data. It can be changed with the setup program.[3]
IBM PCs can control several disk drives marked with the letters A, B, C, D, E... The first drive is the floppy disk drive marked with "A". It is absolutely necessary to install the machine. The second optional floppy disk drive is marked with "B". First hard disk drive is indicated with "C". The other letters (D, E, F, etc.) can indicate further fixed disks or logical disks. For example the first hard disk can be divide into to logical disks with the letters C and D or you can create a RAM-disk in the memory with the letter E which behaves the same way as a real disk but exists only until the power is on.
Earlier, XTs could only handle 360 kbyte floppy disks but with modern controllers they can handle 1.2 and 1.44 Mbyte disks, too. ATs contain one or two 1.2 Mbyte floppy disk drives which can be used in 360 kbyte mode also. Unfortunately, there are a lot of compatibility problem with these two types of floppy disks.
The 5 1/4 inch floppy disk is divided into concentric sectors and blocks with the size of 512 byte. There are two magnetic heads in the drive below and above the disk. The 360 kbyte drives can use DS,DD (Double Sided, Double Density) disks. The 1.2 Mbyte drives work with special PC-AT compatible, or DS,HD (Double Sided, High Density) disks. (They also can use the DS,DD disks in 360 kbyte mode.)
[pic]
5 1/4 inch floppy disk
Floppy disks can be easily damaged. User should not touch the disk surface with hands and should not bend them. It is advisable to put them back into their cover after removing from the drive. If you want to prevent data from accidental erasing you can stick down the write protect slit.
The new 3 1/2 inch floppy disks developed by SONY have a hard (metal or plastic) cover. They have a storage capacity of 720 kbyte (DD) or 1.44 Mbyte (HD). It seems that the new international standard for data storage tends towards 1.44 disks.
Hard disks are similar in size with floppies, but their magnetic coating is finer, more complicated. The thin metal based laps, which contains a magnetic coating, are place in vacuum. Depending on the storage capacity and data access speed, several laps and reading/writing heads are included in one HD. Due to the high quality magnetic coating and sophisticated head moving mechanics very high data density can be produced on them. Nowadays the 20-40 Mbyte hard disks are counted as low capacity because the new machines have 200-600 Mbyte winchesters.
A new disk cannot be used at once. First you have to create the structure of data storage blocks. This is called as formatting. After this you can write the programs or data on the disk to sequences of bytes: to the so called files.
The box of the computer also contains a power supply unit with 150-250 W output.
The monitor is a stand alone unit that is usually placed on the computer itself. The screen controller cards produce the signal for the monitor.[4] They can be operated in two ways:
- Graphic mode: the graphic card stores the brightness and color information of all pixels.
- Character mode: the graphic card store only the code number of the characters. There is a standard for coding characters called ASCII-code (American Standard Code for Information Interchange). It binds the characters to numbers among 0 and 127. The IBM character set contains special symbols, international characters and line drawing signs which are coded from 128 to 255. The character generator produces the bit map of the characters using the stored codes. The CGA-card uses 8x8 matrix, the EGA and VGA have 8x14 bit map and the Hercules works with 9x14 pixels.
Nowadays the VGA cards and monitors are regarded as a standard (640x480 pixels with 16 or 256 colors). The 256 color bitmap means that the color information is stored on one byte for each of the pixels. The true color presentation needs more memory (two or three bytes for each of the pixels). The usual memory sizes of the graphic cards are 512 K, 1 M or 2 M.[5]
The user can communicate with the computer through the keyboard. It has three main parts: the function keys, the typewriter fingerboard and the numeric keypad.
Most of the programs assign similar tasks to the function keys. For example F1 gives the help page almost in every case.
The left hand side part of the keyboard is the same as an American typewriter but there are three alternate keys (, , ) to alternate the effect of the other keys, if they are pressed in the same time. The key is used to "enter" the commands typed in into the computer. clears the character on the left side of the cursor. chooses the capital letters.
The numeric keypad on the right side makes typing of numbers easier. If you press the key the numbers will appear, otherwise the cursor control keys will be effectual. These control keys on some of the keyboards are duplicated.
[pic]
Keyboard of IBM PCs
The function of the special keys is as follows:
: moves the cursor left.
: moves the cursor right.
: moves the cursor up.
: moves the cursor down.
: inserts a space or changes the overwrite/insert mode.
: deletes the character under the cursor.
: moves the cursor to the first character of the line.
: moves the cursor to the last character of the line.
: moves the cursor to the previous page of text.
: moves the cursor to the next page.
: returning ("escaping") from a part of the program.
: prints a hard copy of the screen on the printer.
: freezes the screen until pressing any other key.
+: aborts the execution of the program.
+: echo the screen on the printer (second pressing turns off echoing).
You can access only the characters between 32 and 127 with a normal keyboard. The characters above 127 can be typed out with pressing and then the ASCII-code on the numeric keypad. There are also special programs to redefine the keyboard such as or for the Hungarian characters. You can see the IBM character set in Chapter 1.9.
[pic]
Mouse
The mouse, as an input unit, is used worldwide. One can move the cursor with a mouse on a very comfortable way and can choose from the menus or icons with a simple click. Mouses can be connected to the serial port (COM1 or COM2) and you have to install a mouse driver program in the AUTOEXEC.BAT.
The mouses usually are equipped with three keys but the PC programs use only the left key and rarely the right one.
[pic]
Handy Scanner
Scanners are used to scan pictures and fill the data into the memory as a bitmap. The popular, inexpensive handy scanners can scan only in stripes of maximum 10 cm width. Page scanners can be fed with at least A/4 size sheets.
The resolution of the scanners is given in dpi (dot per inch): e.g., 300, 600, 1200, 2400 dpi.
You can store your images in several file formats (e.g., TIF, GIF, PCX, BMP, IMG, JPEG, etc.) The file size of the high resolution images is very large that is why a few of this file types store the information in a more or less compressed form. (They use only simple methods to compress-decompress the image because the more sophisticated methods are very slow.)
However, if you scanned an image you got only the bitmap copy of it. If your sheet contains printed text, you need a sophisticated OCR (Optical Character Recognition) program to produce the text (character) form of this image. One of the best OCR programs worldwide is the Recognita developed in Hungary.
Printers usually should be linked through the parallel port. Nowadays three types of printers are in use: the dot matrix, the ink jet, and the laser printers. Formerly, daisy-wheel and golf-ball typewriters were often used as printers because of their high quality letters. But they were too slow and could not produce graphics so the laser printers elbowed them out.
[pic]
Dot Matrix Printer
Dot matrix printers have 9-24 pins that strike the bitmap through a ribbon to the paper. They can print characters and graphics, too. Most of them can be fed with both continuous paper and single sheets. In this later case one should feed the paper manually or automatically using an optional cut sheet feeder. Printers equipped with narrow carriage can print 80 characters in a line, ones with broad carriages can print 135 characters.
EPSON printers are the most popular matrix printers throughout the world. The most popular EPSON is the FX-1050 (broad version) and FX-850 (narrow version). It is very simple to use these machines.
When you turn on the computer, the printer gets into the on-line state (the on-line indicator goes on, the printer is ready to print). If you press the ON-LINE button the printer will turn to off-line state. Then you can advance the paper one line by pressing LINE FEED and with a full page by pressing FORM FEED. The LOAD/EJECT button serves for loading or ejecting the paper.
The printing quality also can be selected using the control panel of the printer. There are three characters sets: the simple draft and the two NLQ (Near Letter Quality) sets (Roman and SansSerif). Printing in draft mode is faster than in the others but the quality of the print is poor. The thickness of the characters can be preset in three modes. The normal setting is 10 cpi (character/inch) when the machine prints characters 0.254 inch of width. In the 12 cpi mode the characters have a little less width. The proportional printing means that the characters have different width. There is an other possibility to print more character to a line: the condensed mode with its small letters.
There is an arm on the top right side of the printer which is used to select between the continuous paper and single sheets. The continuous paper should be thread into the cog-wheels on the top of the printer. By pressing the LOAD/EJECT button, paper will be loaded automatically. Pressing of the ON-LINE button has the same effect if the printer is not in on-line mode. When printing has finished, the printer feeds the paper with a few lines to make detaching possible. If you would like to use single sheets it is not necessary to remove the continuous paper. You can thread out the continuous paper by pressing the LOAD/EJECT button and later you can thread back it with the same button.
There are two sets of dip-switches on the right side of the printer. They are used to set up printing parameters that are rarely changed. For example, the international character sets, enlarged or condensed printing after turning on the printer, automatic format feed at the bottom of the page, etc.
Unfortunately, the international character sets do not contain all the special Hungarian characters and they can be downloaded only in draft mode. Therefore, the character ROM usually is replaced with an EPROM in our country. Recently, all EPSON and STAR printer sold in Hungary contains the full Hungarian character set.
The printers of the EPSON LQ series work with 24-29 pins so their prints have a better quality than the FXes, they give the so called letter quality (LQ).
[pic]
Laser Printer
The working concept of the laser printers is similar as the xerox-machines (electrostatic copiers) but they get the signal not from a scanner but from a computer. There was a world standard for these printers: the HP (Hewlett-Packard) LaserJet Plus compatible printer and now there is a new standard: the HP LaserJet III compatible (or HPPCL-5 compatible) machine. All the printers should emulate one of these operating modes.
The resolution of the laser printers is among 300 and 600 dpi. They work in two different ways. In the first case (when printing graphics) the computer produces the bitmap graphics and sends it to the RAM of the printer. In the second case (when printing texts) the computer first downloads the bitmaps of the characters to the memory of the printer and then, when the printing is in progress, the computer sends only the codes of the required character sets and characters. These downloaded fonts are also called as soft fonts and should be distinguished from the hard fonts that are built in the ROM of the printer, or can be loaded from a plug-in ROM-cartridge.
The base memory was usually 512 kbyte that was not enough to print a full page of graphics. The new HP III series comes with a RAM of 1 Mbyte. If the printing speed is not satisfactory, it can be increased by adding more memory (2-4 Mbyte).
The default paper size of this printers (and the word processor programs) is the Letter (8.5x11 “ American size) but in Europe we use A4 size (8.27x11.69 “ or 210x290 mm) papers. Bad paper size setting may cause different printing problems. Use the laser printers with high quality Xerox papers only!
The quality and the costs of the ink jet printers are between the matrix and the laser printers. Their working concept is very interesting: they shoot ink drops to the paper from one or more jets continuously. In this case the print is built up by the drops likewise in a matrix printer by the pins. The only difference is the high quality of the print produced by the jet printers. This method is applicable for producing color printouts. The new version of these printers is called bubble jet printer and it produces better quality printouts than a laser printer.
There are special glossy papers, transparencies, labels for using in laser printers and ink jet printers. Other materials can damage the printers.
Plotters use color pens to draw the picture. Therefore they are suitable in CAD (Computer Assisted Design) applications to draw the plan.
The Operating System
The basic part of the operating system is the ROM-BIOS (Basic Input-Output System) which is placed in the upper 8 kbyte segment of the memory. It contains the programs and tables that are absolutely necessary to operate the computer. After the computer is turned on, the ROM-BIOS checks the memory, the keyboard and runs the setup program if it is requested. Finally, it attempts to load the disk operating system to the RAM from one of the backing stores.
The other part of the operating system can be found on the disk. This is the DOS (Disk Operating System) which can be either from the Microsoft Co. (MS-DOS) or from the IBM Co. (PC-DOS). The name "DOS" comes from the "disk" in two senses: the DOS is placed on a disk and its main function is to handle the disk files.
The ROM-BIOS checks the disk drives in their alphabetical order (A, B, C, ...). If there is a special disk containing the operating system in drive A, it will be loaded. If there is an ordinal disk in this drive the system will halt with the "Non system disk" error message. If drive A is empty, the computer will try to load the system from the next (B) drive and so on. If the computer is equipped with a hard disk drive, usually the OS can be found on it.
The system disk contains a short boot sector that can load the operating system.[6] ("Boot" comes from "bootstrap".) There are two special files on the system disk: IBMBIO.SYS and IBMDOS.SYS. These system files are in fixed positions on the disk and are hidden files. It means that their names do not appear when you ask for the directory of the disk. These names are used in PC-DOS; the MS-DOS equivalents are IO.SYS and MSDOS.SYS. The first file controls the peripherals the second contains the service routines of the DOS. They are also called as resident programs, which means that they always remain in the memory and no program can clear them. After exiting any other program, they become active again.
The most frequently used commands are included in the file. These are the so called internal DOS-commands. The is a semi-resident program which means that it will get damaged if the other program absolutely needs its place in the RAM. In this later case the should be reload after finishing the other program. If the computer does not find the , it sends the "Bad or missing command interpreter" message.
The remaining part of the DOS; the rarely used commands, is called external DOS-commands. They are separate program files on the system disk and they should be load every time you would like to use them.
The data storage structure (logical structure) is universal within a given OS. There is a table, the FAT (File Allocation Table) on each disk that stores the occupation of the blocks and the chaining information of the files (how the blocks of the file come after each other). The files are classified to directories. The main directory, the so called root can contain simple files and directories; these directories can contain other files and directories, and so on.
You can identify the files (and directories) with their name and extension. The filename can consist of maximum 8 characters with certain restrictions (e.g., the first character must be only a letter or a digit, the name should not contain space, etc.). The extension is optional and can be maximum three characters. This extension can be only a notation for a user program. There are some often used symbols (e.g., TXT=text file) but there is no compulsory rule to use them. There are only three extensions which mean something for the operating system: the BAT, COM and EXE extensions are reserved for program capable of running individually; the so called Batch commands (BAT), executable program (EXE) and machine code commands (COM).
The DOS also stores the size of the files in bytes, the time of last updating and some attributes (hidden file, read-only file, etc.).
When the has been loaded, the computer searches for some other files, too. First it checks whether CONFIG.SYS file exists. It is a simple text file with the initial parameters of the system, e.g., maximum number of opening files and temporary buffers, name and location of device drivers to handle the keyboard or screen, usage of RAM-disk, etc.
In the next step the computer searches for the AUTOEXEC.BAT file. If it exists, the computer executes the commands listed in this text file. This file is used to set up the prompt, the path, to load some resident programs and to start a user program (See later).
If there is no AUTOEXEC.BAT file on the disk the computer will ask you for the date and time. If they are correct just press twice, otherwise type in the date and time in the given form:
Current date is Tue 10-3-1989
Enter new date:
Current time is 00:00:10.15
Enter new time:
Then the actual prompt appears with the letter the drive from which the operating system was loaded:
A>
or
C>
You can change the actual disk drive by typing in its letter, a colon and then pressing :
A> C: +
C>
Then you can run programs (files with the extension .BAT, .COM or .EXE) of the root directory by typing in their name (without the extension) and then by pressing . The usage of DOS-command is the same. For example,
C> DIR +
results the execution of the DIR command what lists the directory to the screen.
You can use two jokers (wildcards) in every DOS-command. The * sign substitutes all the characters after the mark. The "?" sign substitutes only the letter where it stands. These signs are very useful to select groups of files. For example,
DIR *.* lists all the files.
DIR *.COM lists all the files with the extension COM.
DIR R*.* lists all the files beginning with R.
DIR R????.* lists all the files named with 5 characters and beginning with R.
Some Important DOS Commands
One of the advantages of placing the operating system on disk is, that it can be updated when a new version comes out. (It should be noted that the ROM-BIOS also can be updated by a new EPROM.) The latest versions of DOS are MS-DOS 5.00, PC-DOS 4.00 and DR-DOS 6.00.
DOS commands consist of an identifier and a list of parameters. We shall use the following notations:
d: Identifier of the disk drive (A:, B: C:). If we do not use the command will be executed on the actual drive.
\ (backslash) Separator between the directory names.
/ (slash) Precedes the optional parameters.
path Route to access a directory.
file, filename Identifier of the file.
ext Extension of the file name.
[..] Optional parameter. (The brackets should not be typed in!)
We can use capital or lower case letters in the commands but it does not mean anything for DOS. The following commands are all available in MS-DOS versions 3.3 or grater, except a few external commands. We shall indicate this limitation in every case.
Internal DOS Commands
CHDIR, CD (CHange DIRectory)
Changing to another directory from the actual one.
Syntax:
CHDIR [d:][path] or CD [d:][path]
Examples:
CD DBASE
Selects the DBASE directory.
CD..
Gets to the directory of the previous level.
CD\
Gets to the root.
CD\WORD
Gets to the WORD directory through the root.
COPY
Copying files to an other place (directory or drive) with the same name or duplicating files with different names. Several files also can be copied to one file.
Syntax:
COPY [d1:][path1]filename1[.ext1] [d2:][p2]filename2[.ext2]
COPY filename1[.ext]+[filename2][.ext]+...
Examples:
COPY a:help.txt c:\dbase\help2.txt
Copies the help.txt file from the A: floppy to the C:\DBASE directory.
COPY a:help.txt c:\dbase
Copies the help.txt on the same name to the DBASE directory.
COPY a:*.* c:\dbase
Copies all the files from A: to the C:\DBASE directory.
COPY f1.txt+f2.txt+f3.txt
Copies the f2.txt and f3.txt files to the end of f1.txt.
DIR
Lists the directory. It types out the names, extensions and creation date of the files. The names of the hidden files do not appear in the list.
Syntax:
DIR [d:][path][filename[.ext]][/P][/W]
Examples:
DIR
Lists the directory.
DIR/P
If the screen is full it will wait for pressing a key to continue listing.
DIR/W
Lists only the filenames but in the full width of the screen.
ERASE
Erases the files from the directory. The command does not erase the files physically, but marks them only as deleted so they can be reconstructed with the UNDELETE command in version 5.0. If you ask for deleting all the files in a directory the computer puts a control question to you: Are you sure (y/n)? The command deletes only the files and not the subdirectories.
Syntax:
ERASE [d:][path][filename[.ext]]
Examples:
ERASE *.bak
Erases all the files with the extension .BAK.
ERASE *.*
Erases all the files in the actual directory.
MKDIR, MD (MaKe DIRectory)
Creates a new subdirectory.
Syntax:
MKDIR [d:]path or MD [d:]path
Example:
MD DOC
Makes the DOC subdirectory in the actual directory.
PATH
Path to access files. If you try to access a file that can be found in an other (un-pathed) directory the computer will not find it. If you gave some paths the computer will continue searching in them, too.
Syntax:
PATH [d:]path[;[d:]path][;...
Example:
PATH C:\DOS;C:\UTIL
Makes searching always possible in the DOS and UTIL directories.
RENAME
Changes the name and/or the extension of a file.
Syntax:
RENAME [d1:][p1]file1[.ext1] [d2:][p2]file2[.ext2]
Example:
RENAME letter.bak letter.doc
Renames letter.bak to letter.doc.
RMDIR, RD (ReMove DIRectory)
Removes a subdirectory. It has no effect if the directory is not empty.
Syntax:
RMDIR [d:]path or RD [d:]path
TYPE
Types out the content of a file to the screen.
Syntax:
TYPE [d:][path]filename[.ext]
Example:
TYPE readme.txt
Lists the readme.txt file to the screen.
Batch Processing
Files with BAT extension are ordinal text files containing lists of DOS commands. If you start a batch-file with typing in its name, the effect will be the same as you would type in the commands included in the file. As you saw formerly, there is a special batch-file, the AUTOEXEC.BAT (AUTOmatic EXECution BATch file) which automatically begins to run after turning on the computer. We, for Example, use the following AUTOEXEC.BAT file:
@echo off turns off listing of the commands.
set path=c:\ms-dos gives the path for accessing the external DOS-commands.
set prompt=$p$g sets up the prompt for appearing the name of the actual directory.
doskey runs the program.
cls clears the screen.
ver shows the DOS version number.
The CONFIG.SYS file
As you know, the CONFIG.SYS is a list of the most important device drivers. On 386 and 486 machines it should be started with the floowing lines:
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386.EXE
DOS=HIGH,UMB
Then you can use for the drivers the upper memory (650 K - 1 M) with the DEVICEHIGH= specification (in the CONFIG.SYS) and the LOADHIGH command (in the AUTOEXEC.BAT). The HIMEM.SYS and EMM386 ensure the the XMS memory handler that is required by the Windows.
External DOS-commands
As we said, the external DOS-commands are stand alone programs with .COM or .EXE extensions. Therefore they can only be accessed if you are in the DOS directory, or their path was formerly given.
DISKCOPY
Copying a floppy disk to an other. If the target disk is not formatted the program will format it. It copies the system and hidden files, too. Only similar types of disks can be copied to each other (e.g., 360 to 360 k, or 1.2 to 1.2 M).
Syntax:
DISKCOPY d: d:
Examples:
DISKCOPY a: b:
Copies the floppy disk in drive A: to the disk in drive B:.
DISKCOPY a: a:
Makes a copy to the same drive (the disks should be exchanged several times).
DOSKEY (MS-DOS 5.00)
Resident program to edit the formerly typed DOS-commands. You can get back the commands to the prompt by pressing cursor up/down and edit them with the cursor left/right, backspace, insert, delete keys.
DOSSHELL (MS-DOS 5.00)
Operating system shell. One can manage the operating system by using menus.
FORMAT
Formatting a floppy disk or a hard disk.
Syntax:
FORMAT [d:][/S][/1][/8][/V][/B][/4]
Examples:
FORMAT a:
Formats the disk in drive A: to 360 K or 1.2 M (depending on the type of the drive).
FORMAT a:/s/v
Transfers the operating system after formatting (/S) and checks it (/V).
FORMAT a:/4
Formats a 360 K disk in an 1.2 M drive.
PRINT
Printing of a text-file to the printer.
Syntax:
PRINT [d:][path]filename[.ext]
UNDELETE (MS-DOS 5.00)
Reconstruction of the files formerly deleted by the ERASE command. The computer lists the erased files one by one. If you choose a file, the computer asks for the first character of the file-name (because it indicates the erased files with a question mark in the first position of their name). If you write something to the disk after erasing a file, this unerased file can be damaged.
Syntax:
UNDELETE [d:][path]
UNFORMAT (MS-DOS 5.00)
Reconstruction of a newly formatted disk. The computer stores a mirror of the disk before formatting and it can repair the disk with these data.
Syntax:
UNFORMAT [d:]
SOME NEW COMMANDS IN MS-DOS 6.2
FORMAT
You can specify the size of the disk, e.g.:
FORMAT A:/F:720 720 Kyte, 3.5 “ floppy disk.
FORMAT A:/F:1440 1,44 Mbyte, 3.5 “ floppy disk.
FORMAT A:/F:360 360 Kyte, 5.25 “ flopy disk.
FORMAT A:/F:1200 1,2 Mbyte 5.25 “ floppy disk.
INTERLNK, INTERSVR
If you connect two machines via their serial ports and you type the
DEVICE=C:\DOS\INTERLNK.EXE
line in the CONFIG.SYS of one of them (and reset this machine), then after starting the INTERSVR.EXE on the other machine, you can access all the disk drives of this computer on the other with, for example, the identifiers I, J, K. This is a very comfortable way to copy large files and installing programs.
MEMMAKER
You can optimize the memory allocation with this program. (It requires a 386 or 486 machine with HIMEM.SYS és EMM386.EXE drivers).
1.4 Norton Commander
[pic]
Starting screen of Norton Commander
Utility programs make the usage of DOS easier and they also give new services. They have friendly user interfaces with menus and icons to handle the operating system. Beside this, they usually contain simple word-processors and disk monitors. These programs are useful not only for the beginner but also for the advanced users or programmers. There are several integrated utilities (e.g., PathMinder, PCTools or the built-in DOSSHELL of MS-DOS 5.0 and 6.0), but the most powerful and popular one of them is the Norton Commander (and the other utilities designed by Peter Norton). We will introduce the latest (V4.0) version of the Norton commander.
We would like to draw your attention to the fact, that due to screen capture necessities, we had to run the Norton commander through MS Windows. The title bar containing the "NC" text on the screens of this chapter, is added by the Windows program itself.
The Norton Commander is a resident program, and can evoked from the AUTOEXEC.BAT also (the main program is called NC.EXE). The DOS prompt can be accessed directly from a Norton Commander session, and this feature is one of the great advantages of this application. Therefore one can use both the commander and the original DOS-commands simultaneously. Anyway, we suggest to acquire the most often used DOS-commands such as DIR, CD, MD, RD, COPY, ERASE FORMAT, etc., because utility programs are not available on every computer, and the DOS commands can be more powerful in certain cases. The program can show the disk directories in two windows, and the main menu at the bottom line of the screen:
F1 Help helps how to use the program.
F2 Menu opens the user defined menu system.
F3 View displays file contents without editing facility.
F4 Edit starts the simple word processor to edit the file.
F5 Copy copies files.
F6 RenMov renames or moves files.
F7 Mkdir creates a new directory.
F8 Delete deletes files.
F9 PullDn switch on the pull down menu system.
F10 Quit exits from the program with setting the memory free.
You can choose between the two windows by pressing the key. If you move the cursor to a directory name and then you press the directory will be opened.
[pic]
Pull-down menu system of Norton Commander (Left and Right)
With the key, you can access the pull-down menu. You can choose an item with the cursor control keys and .
The "Left" and the "Right" submenus are similar, and are used to set-up the parameters for the left and right windows:
Brief: Abridged show. Only the name of the directories and files will appear.
Full: Full show. The size and creation date of the file also will be showed.
Info: Information about the RAM, the size of the active backup device and directory, and about the free memories.
Tree: Tree structure of the active backing store. It shows the sub directories similar as the branches of a tree. You can move the cursor to any directory and then you can see the content of this directory in the other window (if it is active).
quick View: Quick show of the content of files. Uses both display windows. You can see the file-names of the marked area in one of the windows and the other window sows the content of the marked file. This option is very useful if you would like to identify the files on the evidence of their content.
Compressed file: If there are any compressed files (ARJ, ZIP, LZH, etc.) in the directory, you can automatically select them to view.
linK: Linking of PCs. The Norton Commander makes connection of two PCs through their serial ports possible. In this case you can send and receive messages and you can also read and write the hard disk of the other machine.
On/off: With this command you can switch on or off the display window.
The next block of this submenu can be used to set-up the order of appearance of the files.
Name: Shows files in alphabetic order of the filenames.
eXtension: Shows files in alphabetic order of the extensions.
tiMe: Shows files in order of the creation times. The first file in line is the one stored latest.
Size: Shows files in order of the sizes.
Unsorted: Shows the files as it is stored in the harddisk.
Pull-down menu of Norton Commander (Files)
[pic]
Unsorted: Restoring the previous order.
Pull-down menu system of Norton Commander (Files)
The next menu (Files) contains the following items in the first block:
Help: Detailed description of usage.
User menu: Activates a user defined menu. You can create a menu contained your most frequently used programs and you can start them with this menu. (See later how to design this menu.)
View: Shows the content of the selected file without the damage of unfortunate overwriting. The text can be moved by the cursor control keys. Norton Commander recognizes the formats of a few popular database management systems, word processors and image formats, so it can show them without the disturbing control characters. There is an opportunity to get the hexadecimal form of the files, too.
Edit: A simple word processor to edit the selected file. Its works similar to the View option, but it can change the content of the file. If you want to create end edit a new file you have to press the and the keys.
Copy: Copying files. It copies the marked file in one of the windows to the directory showed in the other window. You can copy more than one file, too. To do this you have to mark the files with the key first. (The second pressing of this key unmarks the file.) If you want to copy all the files of a directory, you have to press the gray key (on the numeric keypad). Pressing of the and key makes the use of * and ? jokers possible.
Rename or move: Renaming and moving file(s). The usage is the same as the Copy option. The move command copies the marked files to a given directory and deletes the original.
Make directory: Creation of a new sub directory in the actual directory.
Delete: Deleting files or directories. Selection of files or directories are similar (). You can choose a group by pressing and . If you want to delete the sub directories and it contents of a main directory, you should check the "Include sub directories" check book too.
file Attribute: Setting up or altering attributes of files (Read-only, Archive, System or Hidden).
select Group: Selecting of files for an operation.
deselecT group: Unselecting the previous selections.
Invert selection: you can invert a selected group of files and/or directories by pressing the "*" on the numeric keypad.
reStore selection: You can restore the inversion of the selection also by re-pressing the "*" key on the numeric keypad.
[pic]
Pull-down menu system of Norton Commander (Files)
Quit: Exiting the Norton Commander. This command sets free the whole memory that was occupied by the Norton
The Commands menu gives us some further useful services:
NCD tree: Showing the tree-structure of directories of the actual storage device.
Find file: Showing the localization and creation date of a given file.
History: The program stores all the commands executed since it started. This item gives the list of these commands and the possibility of repeating them.
EGA lines: Setting up more then 25 rows on the screen with EGA or VGA monitors.
system Information: Provides brief information of the hardware components of the computer.
Swap panels: Transposing the contents of the left and right windows.
Panels on/off: Switching on/off the windows.
Compare directories: Comparing the contents of directories.
Terminal emulation: This is a very useful application which allows you to control modem, fax and other serial communication protocols. Using this, you can dial any telephone number automatically, too.
[pic]
Menu files edit: Editing the user defined menu. First the hot key should be specified (this will activate the menu item) and then the commands similarly as in a batch file. (See the two figures above and the Automenus option later.) You can define a use menu by manual editing of the NC.MNU file. This can be found in the directory specified by the "SET NC=" directory. (See later.) This can be done during the installation process of the Norton Commander too.
[pic]Creating a user defined menu for Norton Commander
Pull-down menu of Norton Commander (Options)
Display of the previously defined user menu
eXtension file edit: Giving of extensions for the application programs. For example, if you attach the .DOC extension to the WORD program you can run it by marking a DOC file and pressing . After the program starts it will automatically load the given document.
[pic]
The Options menu
The next menu is the Options in which you can set-up the initial parameters of Norton Commander:
Configuration: Initial settings of the main program:
Screen colors:
1. black & white.
2. color 1 and Color 2. (two sets of color schemas)
3. laptop (portable computer with an LCD monitor).
Screen blank: Sets the screensaver time limit. After this time the monitor shows
the "sky with stars" to take care of the picture tube.
File panel option: Making visible the hidden files. Marking with the key.
Tree panel option: Switching of automatic showing of the content of the directory
marked in the directory tree.
Other option
Menu bar always visible: always displays the pull-down menu (otherwise you can activate it by pressing ).
Auto save setup: Automatic saving of the above mentioned options. If you do not ask for this item, the original setting will remain after reset.
Left handed mouse: Transposing the keys of the mouse.
Fast mouse reset: Connecting of a mouse with some types of computers (e.g., PS2) can cause a delay of several seconds after a DOS command ran. Using this option can eliminate this error.
Printer port
This option should be specified if you want to print files directly from the Norton Commander. It is advisable to print text (ASCII) files only. You must specify the port (LPT or COM) to which the printer is connected.
Editor: You can select different word processor instead of the built-in editor, which will start by pressing the key. The built-in editor is too simple, so it is advisable to setup a more sophisticated program at this point, e.g., Norton Editor (NE).
Confirmation: Using this menu you can specify the commands which must be reinforced by a control command. These commands are Copy, Delete, Move, Delete sub directories, and Exit.
Compression: It is possible to compress files without exiting the Norton Commander. You must copy the compressing and decompressing programs into the Nortons default directory. In this menu you can specify the method of compressing and encrypting of the compressed file with a password.
Auto menus: Switching on/off the display of the automatic menus. If switched on, the user defined menu will be active immediately after Norton Commander loaded. It is very comfortable for the less experienced user to configure the system in such a way that first you make the user menu with the more often used programs, switch on the automenu option and type the NC command line in the AUTOEXEC.BAT. P
Path prompt: Setting on/off showing of the active path in the DOS command prompt.
Key bar: Switching on/off the bottom menu.
Full screen: Showing the left and right window on the full screen or on the upper half of the screen.
Mini status: Setting the appearance of the detailed parameters of the files.
cLock: Switching on/off a clock in the upper right corner of the screen.
Save setup: Saving the configuration data. (This switch has no function if you switch on the auto setup option.)
NC stores the configuration data in a file called NC.INI (the user menu is stored in NC.MNU). Therefore if you started NC from a network server there will be problems with these files (e.g., the other network users can overwrite your NC.* files). Therefore it is worth to set up an environmental variable to determine the place of the initialization files. For this purpose you should add the following line to your AUTOEXEC.BAT:
SET NC=F:\PUBLIC\NC\MACHINE1
It tells to the Norton Commander that your files are in the directory given after the equation sign. The other terminals in the network may use the MACHINE2, MACHINE3, etc. directories. (Or you can specify any other directory also.)
Almost all the network programs use environment variables to store and retrieve the initial settings, screen types, printer drivers for the different terminals.
1.5 Computer Networks
Classification of Networks
Network is a system of communication in which the computers connected onto the network can send and receive electronic information from each other regardless to their physical localization. Using simple data networks such as the telephone network, you can send messages in the form of sounds, texts and pictures, but you should organize the connections. The computer networks contain hardware and software equipments to manage the communication (bridges, routers, manager softwares, etc.). The end equipments are called terminals. There are central computers in several networks for public applications (host, server or mainframe machines).
We can classify networks considering physical localization of the stations as follows:
- local area networks (max. 5 km distance)
- metropolitan networks (max. 25 km distance)
- wide area networks (above 25 km distance).
In star networks the stations can communicate with each other through a central switch which can connect any station to an other one. This structure characterizes the simple data networks.
[pic]
Structure of star networks
[pic]
The hierarchical networks connect the stations to the equipments of a higher level. That is just like a tree. There is usually a mainframe in the root.
Structure of hierarchical networks
In the ring networks each station is connected only to its neighbours. If one of the terminals goes out of order, the network cannot work. (Therefore there is an other variation of it, where the connectors are outside the machines.)
[pic]
Architecture of ring networks
The most popular structure adopted in local area networks is the bus network. In these networks all the stations are connected to a bus thus all the messages appear in every station. Communication on the network is independent from the terminal, the only problem would be if the bus gets damaged.
[pic]
Bus network
The data transfer rate of the networks can be measured by the number of signals transmitted per second. Its unit of measure is called baud. (Usually, 1 baud=1bit/sec).
The transmission can be synchronous when the same clock signal controls all the stations and it can be asynchronous when the pieces of the messages are sent in discretional moments. In this later case the stations should be signalled the beginning and end of data transmission.
The connection can be simplex (one way), half (semi) duplex (the two ways are alternate in time) or duplex (two directional in every time).
You can make, for example, a duplex connection between two IBM PCs through their serial ports with the so called handshake process. In this way there are separate wires for the signal ground, data transmission, ready to accept and end of transmission signals, and acknowledgment of receiving data. Thus you have to use 9 wires in a simple serial connection. The maximal transfer rate is 9600 baud, parity of the bytes can be checked or not, each byte can send information on 7 or 8 bits with 1 or 2 stop bits. You can set up the serial communication setup using DOS command MODE. For example,
MODE COM1:9600,N,8,1
means 9600 baud speed, no parity checking, bytes consisting of 8 bit information with 1 stop bit. This setting should be made on both of the computers after the physical connection was established. This is the simplest way to connect two computers. It is also possible to connect computers through the telephone network by using MODEMs (MODulator-DEModulator). The most popular MODEM is the acoustic coupler which should be connected to the serial port of the computer and then the telephone receiver should be placed on it.
Baseband networks can transfer only one package of information on a cable at the same time. Broadband networks can handle more than one package in a moment using of modulated sinus waves of different frequencies.
The data transfer medium can be twisted pair of wires, coaxial cable, fiber optic cable or radio wave (microwave). Recently the fibre optic cables come into fashion because of their great advantages. For example, they can provide higher speed of communication and galvanic voltage differences never occur, therefore fiber optic cables are ideal to build a network of medium size. Smaller LANs (e.g., in a ward) still use "traditional" cables.
[pic]
The communication can be realized through three main levels:
Organization of network communication
The lowest level is used to send, receive and check the signals. Transferring is managed on the middle level. The end-user contacts only with the highest level that gives advanced services (e.g., for file-handling). These three levels are divided into 7 further layers by the ISO standard (International Standard Organization).
The rules of information interchanging between these levels are prescribed in the so called protocols. These protocols are international standards.
Local Area Networks
To fulfill the needs of wards and clinics of a hospital - which are in close vicinity to each other - the local area networks (LANs) offer the best solution. Its advantage is the possibility of communication between the terminals and the common usage of high capacity backing stores, printers or computers. Therefore the terminals can build up a common database. The local area networks can be connected to other LANs and they can reach national or international networks through special high distance communication networks. In the following we will introduce a few common LAN types.
ArcNet Network
The ArcNet is a baseband bus network with a data transmitting speed of 2.5 Mbaud. Its architecture is very interesting because it looks like a star network, since the terminals are connected to a central unit, the so called hub. However, this unit does not contain any switch. The information flowing in the network appears in all terminals but only the target computer can receive it. There are active hubs to connect 4, 8 or 12 terminals and the maximum number of the stations allowed is 255. "Active" means, that the unit not only distributes the signals, but it gains and reconstructs them, therefore a terminal can be located max. 650 m from the hub. There are also passive hubs (simple distributors) to connect 3 terminals that are close to each other (max. 30 m).
PCs can be connected to the network through an ArcNet-card inserted into one of their expansion slots. This card contains a BNC socket to which a 93 Ohm coaxial cable can be connected. There are also cards with two BNCs to form a small bus network of maximum 8 computers without any hub. In this case the computer should be connected to its neighbours. The 8 bit cards can be used in XTs and ATs, the 16 bit cards (which are faster) are applicable only for ATs. There is a dip switch on the card to set-up the identification number (node address) of the terminal in binary form.
[pic]
Architecture of ArcNet networks
Ethernet Network
[pic]
Ethernet is also a baseband bus network. Its transfer rate is 10 Mbaud. The maximal length of a cable segment is 185 m (thin cable) but more segments can be connected via repeaters. The maximal number of stations is 1024. The medium can be twisted pair, thin coax, standard coax or fibre optic cable.
Architecture of Ethernet network
IBM PCs can be connected to the network via Ethernet-cards. These cards are more expensive than the ArcNet-cards but they are rather suitable for larger and faster networks. Nowadays Ethernet is the most often used network type to link IBM PCs or workstations.
The organization of message transfer is different in these two networks. The ArcNet network uses the token passing method: the right of sending a message goes round and round between the terminals. That is a time-consuming but powerful process. Ethernet manages the communication by collision detection. If two stations send message at the same time both of them must break it and then they begin it again after randomly selected delays. Therefore overtasking significantly reduces the effective transfer rate of the Ethernet networks. Because of this, if more than 16 terminals are connected to one network segment, the data transmitting speed reduces significantly. The 185 m limitation also can be described by the structure of the data transmitted. Each packet contains a header of fixed length. The length of this header is adjusted in such a way, that meanwhile the computer sends the last byte of the header, the first byte should reach the two ends of the segment. This overrides the possibility of data collision mentioned above and increases the speed of transmission.
Linking Computer Networks
As we said, the segments of a local area network can be linked with repeaters (or with hubs). In this case the messages of the terminals appear in all of the segments (but only the target computer can receive and decode it).
If you use bridges between the segments, the signals will go through the bridge if the target station can be fond in the other side of the bridge. This method reduces the chance of overloading. The bridge can be managed locally or by a remote manger computer. Management means that you can program the traffic control functions of the bridge. For example, you determine what terminals may access others. Therefore bridges make the transfer speed faster and provide shelter from illegal intruders.
Routers have more functions than bridges. They can optimize the paths of the information in sophisticated networks. They can find all the different paths for sending information from a unit to an other. They can choose the optimum path or choose another one, if any part of the cabling is damaged.
Gateways are used to connect different types of networks. They are special computers with a program which can transform the protocols of the two networks. Modern network operating systems offer built-in software gateways by developing common communication protocols (ISO standards).
Large networks need a high capacity host computer to store, organize and forward the messages and to offer such services as time-sharing and multitasking. Formerly the VAX minicomputers produced by the DEC (Digital Equipment Corp.) and the IBM mainframes were the most often used hosts. Recently the so called workstations are in general use in distributed networks (where more than one host can be found). These machines have 1-4 microprocessors of high capacity (SPARC, RISC), 32-128 Mbyte RAM, 1-3 Gbyte hard disk and magnetic tape unit, CD-ROM. They use the UNIX operating system.
Today's best network system is the FDDI (Fibre Distributed Data Interface) which can be used in metropolitan networks. For example, the urban network of the University of Debrecen (which is under construction) will be an FDDI main ring established between the institutions. The Ethernet system LANs of the colleges and universities will be connected to this main ring through routers.
The LAN of the University Medical School will be an Ethernet ring. The "ring" means that the two ends of the main segment will be connected to each other through a bridge which will close the circuit if any breakdown occurs. This main ring can be easily reshaped into an FDDI system later. The LANs of the departments will be connected to the main ring directly or through routers.
The wide area networks are provided by common carrier companies. The terminals can join these public networks through an X.25 interface which is in general use. The transmission method of the public packet networks is the so called packet switching which means that the messages are divided into packets of equal lengths and these packets are stored and sent through the nodes of the network to the destination station. Today the transfer rate is only 9600 baud, but 64 kbaud and 1 Mbaud systems are under construction.
One of the most important services of the public packet networks is the electronic male (e-mail). Every end-user has an electronic mail box that can receive or send text files, programs, pictures, sound files, etc. from or to other boxes. Our national e-mail system (ELLA) is able to contact with the large international networks such as INTERNET or BITNET. There are closed networks that use the public network services but they cannot be reached by unauthorized stations (e.g., the academic network of Europe, the so called EARN).
NOVELL Netware
The existing LANs of our university consist of IBM XTs and ATs as terminals, AT 386 and 486 machines with a large hard disk as servers. They are either ArcNet and Ethernet networks. There is a long ArcNet backbone to link the LANs of the clinics. Our computer lab is similar to a clinical network. Nevertheless, clinical networks contain more machines, servers, safety backup stores (streamers, magneto-optical or optical devices). Novell can use either ArcNet or Ethernet network elements. It provides a so called internal bridge which joins an ArcNet and an Ethernet network at the same time.
The Novell Netware (network operating system) is installed on the hard disk of the server machine. The terminals use the MS-DOS operating system which is placed on their boot floppy disk, hard disk or in a special boot EPROM. After booting, two resident programs should be evoked ( and ). contains the network communication protocol meanwhile the establishes the logical connection between the terminal and the server. If you put a system floppy disk into the A: drive with these files and the following AUTOEXEC.BAT, the terminal will be attached to the network automatically:
IPX
NETX
F:
LOGIN
Then you can use your local disk drives as usual with the A:,... E: identifiers. The most important service of the netware is to provide further disk drives (starting from F:) for the terminals with F (or higher) identifier. This disk can be used in common with all the terminals. The user can attach to the network with the LOGIN program and leave it with the LOGOUT. The administrator of the system is the supervisor who controls the rights of the other users with the SYSCON program. The supervisor binds a login name and a password to the users or group of them and he gives the rights to the users in every directory. These rights can be the follows:
R: Read from files.
W: Write to files.
O: Open existing files.
C: Create new files, make new subdirectories.
D: Delete existing files and erase existing subdirectories.
P: Change users' directory rights.
S: Search the directory.
M: Modify file status flags.
P: Parental rights (only for directories)
Su: Supervisory rights (only for directories)
For example, the students can use our network with the "student" login name without any password. In general, a password is required which should be touch-typed because it does not appear on the screen.
If you make any mistake the netware will send the message Access denied, and you will not be attached to the network. In this case you may only use the local peripherals or you can retry attaching by typing the LOGIN command.
The hard disk F: looks just like a local one. The programs are placed in directories and the usage is similar as with a local winchester. But there is a problem in file-handling: if two terminals try to write into the same file at the same moment the system will be frozen. Therefore the application programs must protect their work files from the simultaneous writing. There are a few special directories on the disk:
DOS: contains the and the external DOS-commands.
LOGIN: contains the LOGIN and LOGOUT programs.
MAIL: mail-boxes for the users' messages.
PUBLIC: service programs and network commands.
SYSTEM: service programs and system generator files.
The end-users may use either their own local printer or the network printers connected to the server. The supervisor can create printing formats and queues for the printers with the PRINTCON and PRINTDEF programs. The queue is series of files on the hard disk of the server waiting for printing in a priority order. The users can send files to print on a central printer by using the following command:
NPRINT "file-name" Qqueue-name
(e.g., NPRINT "lectnote.txt" QQ0).
The local printer port also can be re-routed to the central printer. In this case all the printing signals will be transferred to the central printer instead of the local printer. The command is as follows:
CAPTURE Q="queue-name"
(e.g., CAPTURE Q=Q0)
The local printer will be accessible only after typing in the ENDCAP command.
The terminals can send messages to each other with the SEND command:
SEND "message" TO STATION station number or login name
(e.g., SEND "Hello!" TO STATION 1).
The number of the station is not bound to the machine, it depends on the order of login in.
If there are different servers in a large network (e.g., the DOTE LAN where almost every department has a Novell server) you can get the list of the active servers by typing the SLIST command in. If you have access rights on an other server you can access it with the LOGIN “servername”/”username” command. For example, from an othe department you can use our server after the following command:
LOGIN ofk/student
UNIX Operating System
The UNIX operating system came out about 20 years ago. In our country it begins to spread only recently because of the former COCOM prohibitions and the low capacity of our machines.
The UNIX has many similar features with MS-DOS. However the concepts of this operating system are something new: this is a multi-tasking and multi-user system. The file handling features are common in both network systems. The most important difference between these networks is, that the UNIX can run more than one job at the same time. Further similarity is that the UNIX gives also an unfriendly, prompt- and character oriented user interface. In recent times you can use menu controlled shells in UNIX (like the DOSSHELL or the Norton Commander on an MS-DOS machine) and there is a new popular graphic interface the X-WINDOW (corresponding to Microsoft Windows).
The IBM PCs can create a UNIX partition on their hard disk but the UNIX needs larger backing store and memory capacity than MS-DOS. Therefore IBM PCs are not really suitable to use as a stand-alone UNIX station. But if you connect your S-VGA 386 or 486 PC to a UNIX workstation through the serial port or via an Ethernet network and load a terminal emulator software you will get an inexpensive UNIX graphic terminal. In this case you can use your terminal also as an MS-DOS machine with your well-known applications.
The simplest UNIX terminals contain only an alphanumeric display unit and a keyboard. These terminals are controlled by the terminal controller card built into the server machine. The recently used terminals contains a microprocessor and 4-8 Mbyte of RAM. The so called X-terminals produce high quality graphics, for example, 1024x1280 pixel and 256 colours.
UNIX is a much more powerful network operating system than NOVELL. The reason for this is that NOVELL always loads the programs and data into the memory of the terminal first, and then the programs run on the terminal. This is very time-consuming, and it involves the risk of damaging data while transferring. Whereas, UNIX runs the programs in the server machine, the terminal sends only a few bytes to ask for starting a job and then gets back only the results. This method is very fast and there is no risk of any damage of data.
The UNIX uses the so called IP protocol (=Ethernet_II communication standard) of the Ethernet system which is in general use in the computer networks. Novell uses the IPX protocol of Ethernet (=803.2 communication standard).The former versions of NOVELL (2.xx) were not compatible with this protocol but the new generation (3.1, 3.2) can communicate with the UNIX machines through an Ethernet card placed into the NOVELL server.
1.6 Dictionary
A
abandon felad, abbahagy
abort megszakít
absolute abszolút
AC (Alternating Current) váltóáram
accept elfogad
access hozzáférés, bemenet
access time hozzáférési idô
account számla, elszámol
accounting könyvelés, elszámolás
accumulator akkumulátor(regiszter)
acknowledgement elismerés, beismerés, köszönetnyílvánítás
acoustic akusztikai
acoustic coupler akusztikus csatoló
activate aktivál, aktivizál
AD-converter analóg-digitális átalakító
adaptive adaptív
add összead, hozzáad
adder összeadó
addition összeadás
address cím, címzés
address bus címbusz
adjustment kigazítás
advanced haladó, fejlett
aggregate összes, összeg, összegez
aggregating összegzés
AI (Artificial Intelligence) mesterséges intelligencia
ALGOL (ALGOrithmic Language) programozási nyelv neve
algorithm algoritmus
align sorba állít, egyenesbe hoz (pl. margót)
alignment sorba állítás, sorkiegyenlítés
all minden, mindegyik
allocation kiosztás, elhelyezés
alpha alfa
alphanumeric alfanumerikus
alt (alternate) váltó
ALU (Arithmetic and Logic Unit) aritmetikai és logikai egység
analog analóg
analyser analizátor, elemzô
and és, logikai és
annotate jegyzetekkel ellát
annotation megjegyzés, magyarázat
ANSI (American National Standards Institute) Amerikai Szabványügyi Hivatal
APL (A Programming Language) programozási nyelv neve
append mellékel, hozzáfuz (pl. rekordot)
APPLE (Apple Computer Inc.) számítógépgyártó cég
application alkalmazás, használat
application package alkalmazói programcsomag, felhasználói programcsomag
application software alkalmazói program, felhasználói program
arc ív
architecture felépítés, architektúra
archive archív
area terület, felület, felszín
argument argumentum, független változó
array tömb, mátrix, elrendezés
arrow key nyilas (kuzorvezérlô) billentyu
artificial intelligence mesterséges intelligencia
ASCII (American Standard Code for Information Interchange) karakterek szabványos kódrendszere
assembler assembler fordítóprogram
assembly programozási nyelv
assist kisegít, támogat
asynchronous aszinkron
AT (Advanced Technology) IBM személyi számítógép típus
attach hozzácsatol
attribute jellemzô, attribútum
average átlag
axis tengely (koordináta rendszerben)
B
backing store háttértár
backslash fordított per jel (\)
backspace visszaléptetés, visszatörlés (karakter, billentyu)
backtrack visszalép
backtracking visszalépéses keresés
backup tartalék (erôforrás, másolat), biztonsági (erôforrás, másolat), biztonsági másolatot készít
bad rossz
band sáv
banner fejléc, címfej
bar vonal, korlát, rúd, oszlopdiagram
bar code vonalkód
base alap, bázis
baseband alapsáv, alapsávú
baseband network alapsávú hálózat
BASIC (Beginners' All-purpose Symbolic Instruction Code) programozási nyelv neve
bat batch-file kiterjesztése
batch köteg
batch-file kötegelt feldolgozást leíró állomány
batch-processing kötegelt feldolgozás
baud adatátviteli sebesség mértékegysége (bit/sec)
BCD (Binary Coded Decimal) binárisan kódolt decimális számábrázolás
begin elkezd, elkezdôdik
bell csengô, hangjelzés
benchmark program tesztprogram
between között
binary bináris, kettes számrendszerbeli, kétértéku
binary tree bináris fa
BIOS (Basic Input-Output System) alap bemeneti-kimeneti rendszer
bit (Binary digIT) bináris számjegy, tárolóhely egy számjegy számára
bit image bittérképépes kép
bit map bittérkép
blank üres
blink villogás
block blokk
block diagram blokkdiagram
BMDP (BioMeDical Computer Programs) orvosi statisztikai programcsomag
board áramköri lap
bold kövér karakter
boolean logikai
Boolean algebra Boole-algebra, logikai algebra
boot, bootstrap betöltô (a.m. csizmahúzó)
border keret, szegély, határ
both mindkettô
bottom vége, alja vminek
box keretezô négyszög
bracket zárójel
branch elágazás
break szünet, töréspont, félbeszakítás
bridge híd
broadband szélessávú
broadband network szélessávú hálózat
broadcast adás, üzenetközvetítés, musorszórás
browse átnézés, böngészés, olvasgatás
bubble jet printer buboréksugaras nyomtató
bubble memory buborékmemória
bubble sorting buborék rendezés
buffer átmeneti tároló
bug programhiba (a.m. bogár, poloska)
bullet golyó
bus busz, sín
bus terminator buszlezáró, kábelzáró
busbar buszvonal, sínvonal
bypass összekötô út, kitérô
C
cable kábel
cache memory gyorsító tár
CAD (Computer Aided Design) számítógéppel támogatott tervezés
CAI (Computer Assisted Instruction) számítógépes oktatás
CAL (Computer Assisted Learning) számítógépes tanulás
calculator számológép, kalkulátor
CALL (Computer Assisted Language Learning) számítógépes nyelvtanulás
CAM (Computer Aided Manufacturing) számítógéppel támogatott gyártás
cancel érvénytelenít, visszavon
capacity kapacitás, (adat)befogadó képesség
capital nagybetu
capstan görgô, dob
capture begyujtés, elfogás
card kártya
carriage return kocsi vissza (sorvég) jelzô karakter
carrier vivô, vivôfrekvencia
carry átvitel
carry flag átvitel jelzô bit
cartridge kazetta (mágnesszalag, -lemez, nyomtatószalag stb.)
case eset, állapot, tok
cassette kazetta
catalogue katalógus
CD-ROM (Compact Disc Read Only Memory) otikai lemezes tároló
cell cella, sejt
center középpont, középre igazít (szöveget)
centered középre igazított (szöveg)
CGA (Color Graphics Adaptor) színes grafikus kártya
chain lánc, láncolás
change változtatás
channel csatorna
character karakter
character generator karaktergenerátor
character recognition karakterfelismerés
character set karakterkészlet
chart grafikon, táblázat
check ellenôrzés
checksum ellenôrzô összeg
chi-squared distribution khi-négyzet eloszlás
chip integrált áramköri lapka
choice választás, választék
choose választ, kiválaszt
circle kör, körforgás, körbemegy
circuit áramkör, körforgás, kerület
circuit board áramköri lap
clause mellékmondat
clear töröl
click kettyenés (billentyuzet), kattintás (egér)
clipboard kapcsolótábla
Clipper adatbáziskezelô nyelv (fordítóprogram) (a.m. remek dolog)
clock signal órajel
close lezár
cluster fürt(elemzés)
CMI (Computer Managed Instruction) számítógéppel irányított oktatás
co-processor koprocesszor, segédprocesszor
COBOL (COmmon Business-Oriented Language) programnyelv elnevezése
code kód
coding kódolás
colon kettôspont
color szín
column oszlop, hasáb
columnwise oszlopfolytonosan
com (command) parancsállomány kiterjesztése
combine egyesít, vegyít, kombinál
comma vesszô
command parancs, utasítás
command line parancssor
comment megjegyzés
common közös
compact kompakt, összetömörített
compare összehasonlít
compatible kompatibilis, összeegyeztethetô
compile kompilál, lefordít, összeszerkeszt
compiler fordítóprogram, szerkesztôprogram
completion befejezés
component komponens, alkotórész
compose összeállít, összeszed
compute kiszámít
computer számítógép
condensed összenyomott karakter
condition feltétel
conditional feltételes
configuration konfiguráció, alakzat, összeállítás
confirm megerôsít, bizonyít, hitelesít
console kezelôpult
constant konstans, állandó
contain tartalmaz, magában foglal
content tartalom, terjedelem, befogadóképesség
continous folyamatos
continue folytat
control vezérel, ellenôriz, felügyel
control unit vezérlô egység
controller vezérlô, ellenôrzô
convert konvertál, átalakít
converter konverter, átalakító
coordinate koordináta
copy másolat, lemásol, másol
core mag, központi rész
corner sarok
count számolás, számol
counter számláló, számoló, számológép
courir kurir betutípus
cpi (character per inch) nyomtatási karaktersuruség mértékegysége
CPU (Central Processing Unit) központi egység
create létrehoz
criterion feltétel (tbsz. criteria)
CT (Computer Tomograph) számítógépes rétegvizsgáló
ctrl (control) kontrol váltóbillentyu
currency pénzforgalom, valuta
current áram, irány, aktuális
cursor kurzor
curve görbe, görbület, függvényábra
cut sheet feeder lapadagoló (printerhez)
cycle kör, sorozat, ciklus
cylinder henger, dob
D
daisywheel printer margarétatárcsás printer
data (tbsz.) adatok
data analysis adatelemzés
data bus adatbusz, adatsín
data management adatkezelés
data processing adatfeldolgozás
database adatbázis
database language adatbázis kezelô nyelv
date dátum
datum (tbsz.: data) adat, adottság
DC (Direct Current) egyenáram
DD (double density) dupla írássuruségu mágneslemez
debugger hibakeresô (program)
debugging hibakeresés
DEC (Digital Equipment Corp.) számítógépgyártó cég
decimal decimális, tízes számrendszerbeli, tizedesjegy
decision döntés
declaration meghatározás (típus, eljárás stb.), deklaráció
decoder dekódoló
decrease csökkent
decryption titkosítás visszaalakítása
default alapértelmezés
degree of freedom szabadsági fok
del (delete) töröl
delay késleltetés
delete töröl
delimited elhatárolt
delimited file határolójelekkel elválasztott mezôkbôl álló szöveges állomány
delimiter határolójel
density suruség, denzitás
deny tagad, megtagad
depend függ
dependent függô
description leírás
descriptor line leíró sor
desktop publishing kiadványszerkesztés
destination célstation, rendeltetési hely
destroy megsemmisít
deviation szórás, eltérés
device eszköz, szerkezet, készülék
device driver berendezésvezérlô
diagnose diagnosztizál, hibát keres
diagnostic diagnosztikus
diagnostic routine hibakeresô eljárás
digital digitális
digitizer digitalizáló
digitizing pad digitalizáló tábla
diode dióda
dir (directory)
direct access közvetlen hozzáférés
directory katalógus, címjegyzék, könyvtár
disable letilt, megtilt
disassembler gépi kódot assembly nyelvre visszafordító program
disc, disk, diskette lemez
diskcopy lemezmásolat
display kijelzô, display, monitor
distribution eloszlás
divide oszt
division osztás
DMA (Direct Memory Acces) közvetlen memóriahozzáférés
doc (doceumentation) programleírás, dokumentáció
domain tartomány, terület, mágneses domén
DOS (Disk Operating System) lemezes operációs rendszer (IBM)
dot pont, pontoz
dot matrix printer mátrixnyomtató
double dupla
double spacing dupla (2-es) sortávolság (gépírásnál)
down lefelé
download áttöltés
dpi (dot per inch) felbontás mértékegysége nyomtatóknál
draft vázlat, durva karakterkép
drag behúz, vonszol, magával visz
draw rajzol
drill gyakorlás
drive meghajtó, hajtómu, lemezegység
drum dob
DS (Double Sided) kétoldalas mágneslemez
DTP (DeskTop Publishing) kiadványszerkesztés
dump tárkiírás
duplex duplex, kétszeres
dynamic dinamikus, változó
dynamic memory dinamikus memória (pl. RAM)
E
each mindegyik
echo visszajelzés
edge széle vminek
editor szerkesztô
effect hatás
EGA (Enhanced Graphics Adaptor) grafikus kártya típus
eject lapdobás (nyomtatón), kidob (lapot)
elapsed time elhasznált idô, eltelt idô
electric elektromos
electronic elektronikus
electronic circuit elektronikus áramkör
electronic mail elektronikus levelezés, elektronikus posta
element elem
else egyébként, máskülönben
empty üres
EMS (Extended Memory System) kiterjesztett memória kezelô
emulation emuláció
enable felhatalmaz, engedélyez
encode kódol
encoding kódolás
encryption titkosítási kódolás
end vég
enhanced kiemelt, fokozott, megnagyobbított
enhancement fokozás, kiterjesztés, megnagyobbítás
enter beír (pl. parancsot), beléptet, bead
entire egész, teljes
entry beírás, beléptetés, beadás, beadott adat, tétel, belépés
environment környezet
EOF (End Of File) file vége mutató
EOLN (End Of LiNe) sor vége mutató
EPROM (Erasable Programmable Read Only Memory) törölhetô-programozható olvasható memória
equal egyenlô
equipment berendezés
equivalence egyenlôség, ekvivalencia
erase töröl
error hiba
error message hibaüzenet
escape (esc) kiszökik, kilép
even number páros szám
exact pontos, egzakt
exclusive kizáró
exe (executable) végrehajtható állomány kiterjesztése
execute végrehajt
exist létezik
expanded memory kiterjesztett memoria
expansion slot bôvítési hely/rés
expert system szakértô(i) rendszer
expertise szakértelem
explore felderít, kutat
exponential exponenciális
export adatkivitel
expose bemutat
expression kifejezés
extend kiterjeszt
extended memory kiterjesztett memória
extension kiterjesztés
extern, external külsô
extra extra, külön, rendkívüli
extract kiemel, kivon
F
facsimile fakszimile, hasonmás, grafikát továbbító rendszer, (tele)fax
fail elmulaszt, elvét, megbukik
failure hiba, sikertelenség, bukás
false hamis, logikai 0
FAT (File Allocation Table) file helyfoglalási táblázat
feature tulajdonság, jellemzô
feed töltés, befuzés (pl papír befuzése a nyomtatóba)
feedback visszacsatolás
fibre optics száloptika
field mezô
file file, állomány, fájl
file management file-kezelés, állománykezelés
file manager file-kezelô, állománykezelô
filename file-név, állománynév
fill feltölt, betölt, megtölt
filter szur, szurô
financial pénzügyi
find talál, megtalál, megkeres
fit illeszt, egyeztet
fix rögzít
fixed állandó, rögzített, merev
fixed disk merevlemez, winchester
fixed point fixpont, rögzített pont
flag jelzô, jelzôbit
float lebeg, úszik
floating point notation lebegôpontos számábrázolás
floppy hajlékony, laza
floppy disk hajlékony mágneslemez
floppy disk drive hajlékony lemez meghajtó
flops (Floating Point Operations Per Second) másodpercenkénti lebegôpontos muveletek
flow folyamat
flow chart folyamatábra
flow-control folyamatszabályozás, adatáramlás vezérlés
font betukészlet
footer, footnote lábjegyzet
form lap (nyomtatópapír)
form feed laptovábbítás (lap végére)
format formátum, formattálás, lapelrendezés
formula képlet
FORTRAN (FORmula TRANslater) programozási nyelv neve
frame keret, lap, cetli
freeze befagyaszt
frequency frekvencia, gyakoriság
frequency distribution gyakorisági eloszlás
full tele, teljes
function függvény, funkció, muködés
function key funkció billentyu
functional language függvényalapú programozási nyelv
fuse biztosíték
G
game theory játékelmélet
garbage szemét, hulladék, értéktelen információ
garbage collection szemétgyujtés, értéktelen információk kiszurése
gate kapu, logikai kapu, kapuáramkör
gateway átjáró
general általános
get kap, vesz, betölt
global globális, teljes
glossary szógyujtemény
go megy, indul
goal cél
gothic gótikus (karakterkészlet)
goto statement vezérlésátadó utasítás
graph grafikon, diagram
graphic grafikus
graphic mode grafikus üzemmód
graphics card grafikus kártya
gray scale szürkeskála
grid rács, rácsoz
group csoport
H
hack feltör (programot, rendszert)
hacker feltörô (számítógépes betörô)
half fél
halt megállás, leállítás
handle kezel, irányít
handler kezelô, irányító
handshake kézfogás
handy scanner kézi képdigitalizáló
hard disk merevlemez, winchester
hard disk drive merevlemez meghajtó
hardcopy papírmásolat képernyôrôl
hardware hardver
hardwired huzalozott
hazard kockázat, veszély
HD (High Density) nagy írássuruségu (1,2 Mbyte-os) mágneslemez
HDD (hard disk drive) merevlemez egység, winchester
head fej
header fejléc
heap halom(tár)
height magasság
help segítség
hexadecimal tizenhatos számrendszerbeli
hi (HIgh) felsô (byte)
hidden rejtett
hidden file rejtett file
high magas
high resolution nagyfelbontású
high-level programming language magasszintu programozási nyelv
highlight kiemelt rész kivilágított rész
histogram hisztogram
hit leüt (billentyut)
home alaphelyzet
home computer házi számítógép
horizontal vízszintes
host computer gazda számítógép
hub csillagcsatoló
huge óriási
I
I/O (Input/Output) bemeneti-kimeneti
IBM (International Business Machines) számítógépgyártó cég
IC (Integrated Circuit) integrált áramkör
icon ikon, kép, piktogram
identification azonosítás
identifier azonosító
identify azonosít
if statement feltételes szerkezet
ignore figyelmen kívül hagy nem vesz tudomásul, mellôz
image kép
image processing képfeldolgozás
impact printer érintéses nyomtató
import adatbehozatal
incorrect hibás, helytelen
increase megnövel, fokoz, szaporít
increment növekedés
indent bekezdés
index index, mutató
index file index állomány, index file
index register indexregiszter
indexed addressing idexelt címzés
indexed file indexelt állomány, indexelt file
indexed sequential file idexszekvenciális állomány, indexszekvenciális file
indicator jelzô
indirect addressing indirekt címzés
information információ
information technology információtechnológia
initialization inicializálás, kezdôadatok beállítása
initialize inicializál
ink jet printer tintasugaras nyomtató
input bevitel
input device beviteli eszköz
input-output beviteli-kiviteli
ins (insert) inzert, beszúrás
install installál, üzembe helyez
installation installáció, üzembehelyezés
instruction utasítás, parancs, értesítés, oktatás
instrument eszköz
integer egész
integrated circuit integrált áramkör
intensity intezitás
interactive interaktív, párbeszédes
intercept metszéspont
interface interfész, csatlakozási felület
internal belsô
international nemzetközi
interpreter értelmezô
interrupt megszakítás
interrupt handler megszakításkezelô
interrupt request megszakításkérés
interrupt vector megszakítás vektor
introduction bevezetés
inverse inverz
IRQ (Interrupt ReQuest) mregszakításkérés
ISO (International Organization for Standardization) Nemzetközi Szabványügyi Szervezet
IT (Information Technology) információtechnológia
italic dôlt betu, kurzív szedés
item tétel, cikk
iteration iteráció
J
job munka
join illeszt, érintkezik, kapcsolódik
joystick botkormány
jump ugrik
jump instruction ugró utasítás
jumper átkötés
junction érintkezés, átmenet, érintkezési felület
justification sorkizárás, sorkiegyenlítés
justify kizár (sort), kiegyenlít
justyfied kizárt, kiegyenlített
K
K kbyte
key kulcs, billentyu, gomb
keyboard billentyuzet
keypad billentyuzet (kisméretu)
keyword kulcsszó, fenntartott szó
kill kiirtás, megsemmisítés, hatástalanítás
knowledge tudás
knowledge base tudás alapú
L
label címke
LAN (Local Area Network) lokális hálózat
landscape: fekvô formátumú kép ("tájkép")
laptop hordozható számítógép
large nagy
larger than nagyobb mint
laser printer lézer nyomtató, elektrofotografikus nyomtató
latch retesz
layout tervrajz, alaprajz, elrendezés
leave elhagy, kilép
LED (Light Emitting Diode) fényemittáló dióda
left bal, baoldal, baloldalra esô rész
legend felirat, címszöveg
length hosszúság
less than kevesebb mint
letter quality levélminôségu nyomtatás
level szint, színvonal
library könyvtár, programkönyvtár
light pen fényceruza
line vonal, sor
line feed sortovábbítás
line printer sornyomtató
linedraw vonalrajzolás
link lánc, láncol, kapcsolat, kapcsol
link editor szerkesztô-összekapcsoló program
linker összekapcsoló program
LISP (LISt Processing) programozási nyelv neve
list lista, listáz
lo (LOw) alsó byte
load betölt, tölt
local helyi
local area network helyi számítógép hálózat, lokális hálózat
locate elhelyez, helyet megállapít
location elhelyezkedés
lock zár, zárol
logarithm logaritmus
logaritmic logartimikus
logical function logikai függvény
logical operation logikai muvelet
logical programming laguage logikai programozási nyelv
login bejelentkezés, belépés
logout kijelentkezés, kilépés
look up keres
low alacsony
low-level programming language alacsony szintu programozási nyelv
lowcase, lower case kisbetus
LQ (Letter Quality) levélminôségu
LSI (Large Scale of Integration) nagyfokú integráció
M
M Mbyte
machine code gépikód
macro makroutasítás
macro assembler makroutasításos assembler
magnetic mágneses
magnetic card mágneskártya
magnetic tape mágnesszalag
mail posta
mailbox postaláda, elektronikus levelezés tárterülete
mailmerge körlevél készítés
main fô
main memory központi tár
main program fôprogram
main storage, main store központi tár
mainframe nagyszámítógép, nagyszámítógép központi egysége, nagyszámítógépes rendszer
maintenance karbantartás
manage kezel, vezet, végrehajt, intéz
manager kezelô, vezetô, végrehajtó, intézô
manual kézikönyv, kezelési útmutató, manuális
map térkép, tervrajz
margin margó
mark jel, jelöl, megjelöl, kijelöl
maskable interrupt maszkolható megszakítás
match egyezés, illeszkedés, egyeztet, ösz-szeilleszt
matrix printer mátrixnyomtató
maximal maximális
mean jelentés, középérték, átlag
measure méret, mérték, mér
measurement mérés
memory memória
menu menü, étlap
menu-driven menüvezérelt
message üzenet
MGP (Monochrom Graphics Adaptor) monokróm grafikus kártya
microcomputer mikroszámítógép
micropocessor mikroprocesszor
minicomputer miniszámítógép
minimal minimális
mnemonic emlékezteterôsítô
mode mód
MODEM (MOdulator DEModulator) telefonos adatátvivô eszköz
modification módosítás, meghatározás, változtatás, mérséklés
modify módosít, meghatároz, mérsékel
modular programming moduláris programozás
modulo operation modulusképzés, maradékos osztás
monitor monitor, képernyôs megjelenítô, felügyelô program
monitorizing monitorozás, felügyelés
monochrom monokróm
mother board alaplap
mouse egér
move mozgat, elmozgat
multi-tasking egyideju végrehajtás, párhuzamos végrehajtás
multi-user system többfelhasználós rendszer
multiplexer adatbegyujtô
multiplication szorzás
multiply szoroz
multiprogramming multiprogramozás
mute elnémít
N
name név
natural természetes
natural language természetes nyelv
natural language interface természetes nyelvi interface
near letter quality közel levélminôségu (nyomtatás)
negate tagad
negation tagadás, negáció
nest beágyazás
netware hálózati operációs rendszer (NOVELL)
network hálózat
new új
next következô
NeXT nagyteljesítményu mikroszámítógép típus
NLQ (Near Letter Quality) közel levélminôségu (nyomtatás)
No. sorszám
node csomópontcsúcs
notebook kisméretu személyi számítógép
non-impact printer nem érintéses nyomtató
non-maskable interrupt nemmaszkolható megszakítás
none egyik sem
nor kizáró vagy
normal normális
not nem, logikai nem
number szám
numeric numerikus, számjegyes
numeric processor numerikus processzor, ko-processzor, segédprocesszor
O
object cél, tárgy, téma
object code célkód
object-oriented programming objektum orientált programozás
odd number páratlan szám
off-line kikapcsolt, lekapcsolt
old régi
omit elhagy, elmulaszt, kihagy, kifelejt
on-line bekapcsolt, rákapcsolt
open nyitott, nyit, megnyit
operating system operációs rendszer
operation muvelet
optical optikai
optical disk optikai lemez
optical storage optikai tároló
option opció, választási lehetôség
optional opcionális, választható
or vagy, logikai vagy
order sorrend, rendez
ordering rendezés, sorbaállítás
organize szervez
OS (Operating System) operációs rendeszer
other egyéb
outline vázlat, kivonat, körvonal
output kimenet
overflow túlcsordulás
overlap átlapolás, többszörör muveletvégrehajtás, párhuzamos muveletvégrehajtás
overlay átfedés, többszörös memóriakihasználás
overwrite felülír
P
pack tömörít
packed tömörített
page lap, oldal
page number oldalszám, lapszám
paired páros
paired t-probe egymintás t-próba
palmtop egészen kisméretu PC
pan pásztáz
panel panel, áramköri lap, kapcsolótábla
paragraph paragrafus, bekezdés, szakasz
parallel párhuzamos
parallel port párhuzamos port
parameter paraméter, segédváltozó
park parkol
parser mondatelemzô
parsing mondatelemzés
pass átfutás, átmenet, átvizsgálás, levizsgálás
password jelszó
path út, útvonal, elérési út
pathway út, útvonal
pattern mintázat, alakzat
pattern recognition alakfelismerés
pause szünet
PC (Personal Computer) személyi számítógép
peek memóriatartalom kiolvasása
percent százalék
peripheral periféria, perifériális
personal computer személyi számítógép
pica ciceró betu
picture kép
picture processing képfeldolgozás
pie kördiagram
pin tu, érintkezô
pipeline csôvezeték, adatcsatorna
pitch osztásköz, suruség
pixel képpont
placement elhelyezés
plotter rajzgép
plug dugasz, csatlakozó
point pont
pointer mutató
poke memóriatartalom beírása
polygon sokszög
polyline sokszögvonal
pop lekap, veremtárból kivesz
port bemeneti-kimeneti kapu, perifériaillesztô
portable hordozható, átvihetô, gépfüggetlen
portrait: álló formátumú ("portré") kép
position helyzet, helyi érték, pozocionál
potential potenciál, lehetôség
power energia, meghajtás, hatvány
power supply energiaellátás
precision pontosság
predicate predikátum, állítás, kijelentés
press nyom, lenyom
previous elôzô
primary elsôdleges, fô
primary storage fôtár
print nyomtat, printel
printed circuit nyomtatott áramkör
printer nyomtató
priority prioritás
probability valószínuség
probably valószínuleg
procedure eljárás, procedúra
process folyamat, eljárás, feldolgoz
processing feldolgozás
professional szakmai, szakértôi
program counter programszámláló
programmer programozó
programming language programozási nyelv
PROLOG (PROgramming in LOGic) logikai programozási nyelv neve
prompt parancsbeírási hely, készenléti üzenet
proof biztos, ellenálló
proper valódi, igazi, megfelelô
proportional aránylagos
protect véd
protection védelem
protocol protokoll, eljárásszabályzat
PS (Personal System) IBM személyi számítógép-család
pseudocode pszeudokód
public közös, nyilvános
pulse impulzus
punched card lyukkártya
push nyom, benyom, veremtárba helyez
put tesz, helyez
Q
quality minôség
query kérdés
queue sor, várakozási lista, sorba áll
quick reference gyors referencia
quit kilép
R
RAM (Random Access Memory) véletelen hozzáférésu tároló, tetszôleges hozzáférésu tároló
random véletlen, véletlenszeru
range tartomány, kiterjedés, értékkészlet
rank rang
rank correlation rangkorreláció
raster raszter
raster scanning raszter pásztázás
rate ráta, arány, mérték
read olvas, beolvas
read-only csak olvasható
ready kész
real number valós szám
real-time valós ideju
recall visszahív
receive vesz, kap, kézhez kap
recognize felismer
record rekord
recover helyrehoz, helyreállít
reference referencia, hivatkozás, tájékozatatás
reformat újraformátumozás
register regiszter
regression regresszió
relation reláció, kapcsolat
relational database relációs adatbázis
relay relé, közvetítô
release felszabadít, kikapcsol, megenged
rem (remark) megjegyzés
remote távoli
remove eltávolít
rename átnevez
repaginate újrasorszámoz (lapokat)
repeat ismétel
repeater jelismétlô csatoló
repetition ismétlés
replace helyettesít
replicate másolatot készít
report jelent
request kérés
reset újraindít, alaphelyzetbe hoz
resident rezidens, tárban maradó
resolution felbontás, megoldás, képfelbontás
rest maradék, maradvány, hátralevô
restore helyreállít, visszaállít, újra berak
restrict korlátoz, megszorít
retrieve betölt, visszatölt, visszaszerez
retry újra megpróbál
return visszatér
reverse ellekezôje, fordítottja, ellenkezôjére változtat, visszafordít
ribbon szalag, írószalag, printer szalag
right jobb, jobboldali, jobboldali maradék
ring gyuru
ring network gyuruhálózat
rise emelkedik
risk veszély
ROM (Read Only Memory) csak olvasható memória
roman antikva betutípus
room hely, tér
root gyökér, fastruktúra kindulópontja
round kerekít
route útvonal
routin rutin
router útvonalválasztó csatoló
routing útvonalválasztás, üzenetküldés, irányítás
row sor
rowwise sorfolytonos
ruler vonalzó
run fut, programindítás
running programfutás
running head futófejléc
runtime futási idôbeli, futási idô
runtime error futási programhiba
S
safe biztos, veszélytelen, biztonságos
safety biztonság
same ugyanaz
sample példa, minta
sampling mintavételezés
save mentés, kimentés
scale skála
scanner pásztázó, letapogató, képdigitalizáló készülék, lexikai elemzô, átolvasó
scientific tudományos
scientific notation exponenciális számábrázolás
scope érvényességi terület, hatáskör, kiterjedés
scrap hulladék
screen képernyô, szurô
script kézirás, kézirat
scroll képernyôgörgetés
SD (Single Density) egyszeres írássuruségu mágneslemes
SD (Standard Deviation) szórás
SDF (System Data Format) szabványos szöveges adatállomány
search keres
searching keresés
sector szektor, körcikk
security biztonság
seek keres
seek time keresési idô
segment szegmens, metszet, szelet, rész
select kiválaszt
selection kiválasztás
semantical szemantikai, jelentéstani
semantics szemantika, jelentéstan
semicolon pontosvesszô
semiconductor félvezetô
send küld
sequence szekvencia, sorrend, sorozat
sequential szekvenciális, sorrendi
serial sorozat-, sorozatos, sorrendi, soros
serial acces soros hozzáférés
serial interface soros interface
serial number sorozatszám
serial port soros port
series sor, sorozat, hatvány
server szerver, kiszolgáló
session munkaszakasz
set halmaz, beállít, kiszed (betut)
set up beállít
setup beállítás
shadow árnyék, árnyékol, árnyal
sheet lap, ív
shell váz
shift váltó, változtat, eltol
shift register
sign jel, jelzés, elôjel, jelez
signal jel, jelzés, jelez
significance szignifikancia, fontosság
signing-on message bejelentkezô üzenet
simplex szimplex
simulation szimuláció
simulator szimulátor
single spacing egyes sortávolság (gépírásnál)
size méret
skip átugrik, átlép
slash per jel (/)
slot rés, nyílás
smoothing simítás
software szoftver
software package szoftvercsomag, alkalmazói program
software tool szoftverfejlesztési eszköz
sort rendez
sorting rendezés
source forrás
source code forráskód
space üres karakter, térköz, hely
space bar szóköz billentyu
spacing ritkítás, térköz, sortávolság
speech synthesis beszédszintetizálás
speed sebesség
split szétválaszt, szétoszt
split screen osztott képernyô
spread kiterjeszt
spreadsheet táblázatos kalkulációs program
sprite mozgatható grafikai figura
SQL (Structured Query Language) struktúrált adatbázis-lekérdezô neylv
square négyzet
square root négyzetgyök
SS (single sided) egyoldalas mágneslemez
stack veremtár
stack-pointer veremtár mutató
stacked bar egymásra rakott oszlopdiagram
stand-alone magában álló
standard szabvány
standard deviation szórás
standby készenlét
star network csillaghálózat
start kezd, rajtol
statement állítás, kijelentés, parancs
stationery levélpapír
statistical methods statisztikai eljárások
statistics statisztika
status állapot, státusz
status line állapotjelzô sor
step lépés
stepwise lépésenkénti
stochastic szotchasztikus
stochastic process sztochasztikus folyamat
store tárol, tároló, tár
stored program tárolt program
storing device tárolóeszköz
streamer sztrímer, szalagos adattömegtároló
strike üt, leüt (billentyut)
strikethrough áthúzott
string sztring, karakterfuzér, jelsorozat
stroke ütés, leütés, billentyuzés
stroked font vektorral megadott karakterkészlet
structure struktúra, szerkezet
structured programming struktúrált programozás
Student's t-distribution normális eloszlás
style stílus
stylesheet stíluslap
subroutin szubrutin
subscript alsó index
subset részhalmaz
substring részsztring
subtitle alcím
subtotal részösszeg
subtract kivon
subtraction kivonás
suffix toldalék
sum összeg, összegez
supercomputer szuperszámítógép
superscript felsô index
support támogat
sure biztos
suspend félbeszakít, felfüggeszt
switch kapcsoló, kapcsol
symbol jel, szimbólum
synchron szinkron
synchronization szinkronizálás
syntactical mondattani
syntax mondattan, szintaktika
synthetiser szintetizátor
synthetize szintetizál
system rendszer
system disk rendszerlemez
T
t-distribution normális eloszlás
tab (tabulator) tabulátor
table táblázat
table of contents tartalomjegyzék
tabulate tabulál, táblázatba foglal
tail farok, listatörzs
tape szalag
target célpont
task feladat
technology technológia
template sablon
terminal Terminal, végstation
terminate befejez
termination befejezôdés, befejezés
terminator lezáró szimbólum, kábelzáró
test teszt
text szöveg
text editor szövegszerkesztô
text processing szövegfeldolgozás
text-file szöveges állomány
then akkor, azután
theorem tétel
theory elmélet
t3D három dimenziós
tick ketyegés
time series idôsor
time sharing idôosztás
timeout idôtúllépés
title cím
toggle kapcsoló
token szimbólum, programalapelem
tool szerszám, segédeszköz
top tetô, csúcs, legmagasabb
topic tárgy, téma
topology topológia
total összes, teljes, összeg, összegez
touchpad érintésre muködô adatbeviteli egység
trace nyomon követ, lépésenként hajt végre
trace program nyomkövetô program
tractor traktor, papírtovábbító
transceiver adóvevô
transducer transzduktor, jelátalakító
transfer átvitel, átvisz
transfer rate átviteli sebesség
transistor tranzisztor
translate fordítás, fordít
translator fordítóprogram, transzlátor
transparent átlátszó, áttetszô
transpose áttesz, átvisz, transzponál
tree fa
tree search fa-keresés
trend irányvonal, tart vmerre
trim lerövidít
trouble shooting hibakeresés
true igaz, logikai igaz érték
TTL (Transistor-Transistor Logic)
turn off kikapcsol
turn on bekapcsol
turtle graphics teknôsbéka grafika
tutorial oktatóprogram
txt (text) szöveges állomány kiterjesztése
type típus
type in begépel
typewriter írógép
typewriter terminal írógépTerminal, távgépíró, teletex
U
underline aláhúz
underlined aláhúzott karakter
underscore aláhúz
undo érvényteleníti a legutóbbi muveletet
union egyesítés, unió
unique egyedi
unit egység, elem, modul
unpack szétpakolás, lazítás
unpaired t-probe kétmintás t-próba
unprotect védelmet felold
up felfelé
upcase nagybetus
update felfrissít, újraír
upper felsô
upper case nagybetus
user felhasználó
user interface felhasználói interfész
user-friendly felhasználóbarát
utility program segédprogram
V
validity érvényesség
value érték
variable változó
VDU (Video Display Unit) képernyôs megjelenítô
vector vektor
verify bizonyít, ellenôriz
version verzió
version number verziószám
vertical függôleges
view nézet
virtual memory virtuális tár
virus vírus
VLSI (Very Large Scale of Integration) nagyon nagyfokú integráció
voice recognition beszédfelismerés
W
wait vár
wait list várakozási lista
wand vonalkódolvasó
weight súly
weighted súlyozott
which amely
while amíg
width szélesség
winchester merevlemez egység
window ablak
wire huzal
word szó
word processor szövegfeldolgozó
work file munkaállomány
worksheet munkalap
workstation munkaállomás
worm optikai tár, számítógépféreg
wrap szótördelés
X
XT IBM mikroszámítógép típus
Z
zero nulla
zero flag nullajelzô bit
zoom nagyítás
1.7 Glossary
Access time: The time required to obtain data from main memory or a storage device, such as a floppy diskette or a hard disk.
Acoustic coupler: A device for transmitting data over phone lines by converting electrical signals into audio signals, and vice versa. See data communications and modem.
Applications: A specific program or task, such as sorting employee records, to which a computer solution can be applied.
Application program: A computer program designed to meet specific user needs such as a program that controls inventory or monitors a manufacturing process.
Arcnet: Simple computer network of star topology. The terminals are connected to each other with coaxial cable via hubs. Its transfer rate is 2.5 Mbaud, the maximum number of the users is 255.
Architecture: In the case of computers, architecture often refers to the design or organization of the central processing unit (CPU).
Artificial Intelligence (AI): Methods of solving difficult problems by the computer. Its main fields are such as game theory, decision making, learning systems, expert systems, optical recognition, natural language interfaces, machine translation, speech understanding and speech generating, etc.
ASCII (American Standard Code for Information Interchange): Code that has assigned a binary number to each alphanumeric character and several non-printing characters used to control printers and communication devices. The binary number (code) assigned to each alphanumeric character is called ASCII code (e.g., A=65, B=66, C=67, etc.).
ASCII keyboard: A keyboard that sends an ASCII character to a computer when the user presses the corresponding key.
Assembler: Program that compiles an assembler source program to a machine code object program.
Assembly: Low level programming language.
Asynchronous: A communications method in which data is sent as soon as it is ready, in contrast to methods where data is sent at fixed intervals.
AT (Advanced Technology): Personal computer type which is operated by the Intel 80286 processor
AUTOEXEC.BAT: A special batch file with DOS commands that will be executed during the boot-up process.
Background: Refers to one or more non-interactive services running on a personal computer while the user is using another interactive (foreground) service.
Background processing: The automatic execution of a low-priority computer program when higher priority programs are not using the system's resources. See foreground processing.
Backup: Copying of one or more files onto a storage medium for safekeeping, in case if the original get damaged or lost.
BASIC: (Beginners' All-purpose Symbolic Instruction Code) a widely used interactive programming language developed by Dartmouth College by János Kemény. It is specially designed for personal computers and beginners.
Batch processing: The technique of executing a set of computer programs without human interaction or direction during their execution. Under certain conditions, direct interaction is possible.
Baud: Unit of data transmitting and receiving speed, roughly equal to a single bit per second. Common Baud rates are 110, 300, 1,200, 2,400, 4,800, and 9,600.
Bidirectional: (1) Ability to transfer data in either direction, especially on a bus. (2) Ability of a print head to print from right to left and from left to right, which increases print speed.
Binary: (1) Number system with only two digits - 0 and 1 - in which each symbol represents a decimal power of two. (2) Any system that has only two possible states or levels, such as a switch that is either on or off. This is represented in a computer circuit by the presence of current (equivalent to "l") or its absence (equivalent to "0"). All computer programs are executed in binary form.
Bit: Binary digit, which can have only two possible values - 0 or 1. It is the smallest unit of data recognized by the computer All data (letters, numerals, symbols) handled by a computer are digitized, i.e., expressed entirely as a combination of bits - Os and ls.
Bit-map graphics: A technology that allows control of individual pixels on a display screen to produce graphic elements of very good resolution, permitting accurate reproduction of arcs, circles, sine waves, or other curved images that block-addressing technology cannot accurately display.
Board: Also circuit board. A plastic resin board containing electronic components such as chips and the electronic circuits necessary to connect them. See option module.
Bubble jet printer: New version of ink jet printers. It shoots hot ink bubbles onto the paper. Its resolution is between 300-400 dpi.
Buffer: A temporary storage area for data, frequently used to hold data passed between computers or other devices, such as printers, which operate at different speeds or different times.
Bus: A group of parallel electrical connections that carry signals between computer components or devices.
Byte: The number of bits used to represent a character For personal computers, a byte is usually eight bits so it can represent a number between 0 and 255.
C: A high power, low level programming language that supports both the structured programming and the effective using of the processor. Therefore, it is the most popular language of the PCs and UNIX workstations.
Cache: Memory that accelerates disk operations by buffering data. It can be created in the RAM by using a device driver (e.g., SMARTDRV.EXE). The new 386 and 486 machines automatically create it in a separate RAM chip.
Cathode-ray tube (CRT): A vacuum tube that generates and guides electrons onto a fluorescent screen to produce such images as characters or graphic displays on video display screens.
Central processing unit (CPU): Electronic component in a computer which control the transfer of data and perform arithmetic and logic calculations.
CD-ROM: Storage device that uses optical compact discs of 600 Mbyte capacity. Commonly used media to distribute large databases such as dictionaries, encyclopedias, bibliographies. Originally, it was read only memory but the new versions are writable one or more times by the user.
CGA (Color Graphics Adapter): Graphic card of the first ATs. Its resolution is 640x200 (in two color mode) or 320x200 (in four color mode)
Character: A printable letter (A-Z), numeral (0-9), or symbol (, % $ .) used to represent data, or text symbols that are not displayed on screen or printouts, such as a space, tab, or carriage return.
Character code: A code that assigns numerical values to characters, such as ASCII code.
Character printer: A printer that prints one character at a time like a typewriter See lineprinter
Chip: A piece of semiconductor material containing microscopic integrated circuits.
Circuit: (1) A system of semiconductors and related electrical elements through which current flows. (2) In data communications, the electrical path providing one-way or two-way communication between two points.
COBOL: (COmmon Business-Oriented Language) A high-level programming language developed for business applications involving complex data records (such as personnel files or customer accounts) and large amounts of printed output.
Command: A user instruction to the computer, generally given through a keyboard, which can be a word, mnemonic, or character that causes a computer to perform a predefined operation.
Compatibility: (1) The ability of an instruction, program, or component to be used on more than one computer (2) The ability of computers to work with other computers that are not necessarily similar in design or capabilities.
Compiler: A program that translates a source code (text-file) to an object code. Then a linker program generates the machine code program from the object code using a library of routines.
Computer network: An interconnection of computer systems, terminals, and communication facilities.
CONFIG.SYS: A text file with special DOS commands which are executed when the computer is booting up. It also specifies device drivers for your computer. See also Device driver.
Configuration: The assortment of equipment (disks, diskettes, printers, etc.,) in a particular system.
Co-processor: (1) A chip that can make mathematical operations faster. There are just as many types of it as the processors (8087 for XT, 80287 for AT286, 80387 for AT386, etc.). It should be plugged in the appropriate socket on the mother-board. (2) Any microprocessor, which can take over some of the work of the CPU. (E.g. floating point and graphical co-processors.)
Core: The older type of non-volatile computer memory made of ferrite rings that represents binary data by switching the direction of polarity of magnetic cores. Most modern computers use integrated circuits, which are faster than core memory, but volatile.
CPI: See Pitch.
CP/M (Control Program for Microprocessors): An operating system that was used by many 8 bit personal computers.
CPU: See central processing unit.
CRT: See cathode-ray tube.
Cursor: A movable, blinking marker - usually a box or a line - on the terminal video screen that defines the next point of character entry or change.
Daisywheel: A print head that forms full characters rather than characters formed of dots. It is shaped like a wheel with many spokes, with a letter, numeral, or symbol at the end of each spoke. The printing technology is the same as a typewriter. See dot-matrix printer.
Data: Facts, numbers, letters and symbols stored in the computer. For personal computer users, data can be thought of as the basic elements of information used, created or otherwise processed by an application program. Examples of data are the employee names, weekly deductions from salary, projected sales and fuel consumption.
Database: A large collection of organized data that is required to perform a task. Typical examples are personnel files or stock quotations.
Data communication: The movement of coded data from a sender to a receiver by means of electrically transmitted signals.
Data diskette: A diskette that is used entirely or primarily to contain data files.
Data processing: The application in which a computer works primarily with numerical data. Many computers can perform data processing and word processing.
DEBUG: Simple monitor program of the MS-DOS.
Debugger: A program which can search for the mistakes ("bugs") in a program.
Dedicated computer: A computer built for one special function such as controlling laboratory equipments.
Delimited file: Compact file format for transferring data between database management systems, spreadsheets, etc. The character series are quoted, the numbers and the pieces of data (fields) are separated with a delimiter (e.g., with commas).
Desktop Publishing (DTP) System: Computer system with high resolution monitor, printer and scanner. DTP programs (Xerox Ventura, Aldous PageMaker, etc.) show the same picture that will be printed, and they allows editing texts and images in various formats.
Device: In computers, a piece of hardware that performs a specific function. Input devices (e.g., keyboard) are used to get data into the CPU. Output devices (e.g., printers or display monitors) are used to take data out of a computer in some usable form. Input/output devices (e.g., terminal or disk drive) are able to perform both input and output of data.
Device driver: See driver.
Diagnostic: A program that checks the operation of a device, board or other component for malfunctions and errors, and reports its findings.
Direct memory access (DMA): A method for transferring data to or from a computer's memory without CPU intervention.
Disk: A rigid, flat, circular plate with a magnetic coating for storing data. Physical size and storage capacity of disks can vary.
Disk/diskette drive: A unit used to read data from or write data onto one or more diskette.
Diskette: A flexible, flat, circular plate permanently housed in a black paper envelope with magnetic coating that stores data and software. Standard sizes are 5 1/4-inches and 3 1/2 inches in diameter.
Display screen: A device that provides a visual representation of data; a TV like screen. See cathode-ray tube.
Distributed data processing: A computing approach, where an organization uses computers in more than one location, rather than one large computer in a single location.
DMA: See direct memory access.
DOS (Disk Operating System): Trademark of the operating system of the IBM PCs. It has two versions: PC-DOS and MS-DOS (Microsoft-DOS).
Dot-matrix printer: A printer that forms characters from a two-dimensional array of dots. More dots in a given space produce characters that are more legible. See also daisywheel.
Double density: Special recording method for diskettes that allows them to store twice as much data as in normal, or single-density recordings.
Downtime: Period of time when a device is switched off.
DPI (Dot Per Inch): Unit of measurement for the resolution of the printers and scanners. See Resolution.
Draft-quality printer: A printer, usually high-speed, that produces characters of lesser quality than a typewriter. See letter-quality printer.
Drive: A peripheral device that holds a disk or diskette so that the computer can read data from and write data onto them.
Driver: A program that allows the operating system to communicate with a peripheral device. The program usually has SYS, EXE or COM extension. See also CONFIG.SYS.
Electronic mail (e-mail): A feature that allows short memos or messages to be sent to another computer via cable.
EMS: See expanded memory.
Emulator: A program that allows a computer to imitate a different system, thus enabling different systems to use the same data and programs to achieve the same results; but with possibly different performance rates.
EPROM (Erasable Programmable Read Only Memory): A memory chip that can be used in the same way as a ROM chip. The only difference is that its content can be clear with UV-light and then new data can be fed into it.
Ergonomics: The science of human engineering which combines the study of human-body mechanics and physical limitations with industrial psychology. Constant work with computers can lead to health problems in some users such as: eyestrain; neck and back pain; hand, wrist and elbow pain; stress; tension headaches, dizziness, nausea, tension and irritability.
Error message: Text displayed by the computer when an incorrect command is typed, which explains the problem and indicates what to do next.
Ethernet: Local area network of bus topology. Its transfer rate is 10 Mbaud, the maximal number of terminals is 1024. It can be used by both Novell Netware and UNIX.
Expanded memory (EMS): DOS cannot use the memory above 640 Kbyte. The EMS manager located in the upper memory block divide this memory to pages and when a program requires the content of the EMS the manager copies it to the upper memory block where DOS can access it. The EMM386.EXE program (part of DOS) can be used only on 386 and 486 machines, the 286 ATs need a different program. Other method of using this memory is called extended memory (XMS).
Expansion card: Electric board (controller card) that can be plugged into an expansions slot. The disk controller and the graphic card are essential for operating the computer. The input/output card is used to connect the peripherals (e.g., printer, mouse) to the computer. Some other peripherals (e.g., scanners) have their own controller card.
Expansion slot: Socket on the mother board for plugging expansion cards into it. Usually there are 8 expansion slots on the mother board.
Export: Generate files that can be read by an other application program. See also import.
Extended memory (XMS): One of the methods of using the memory above 640 Kbyte in ATs. The XMS memory manager (HIMEM.SYS) ensure accessing all the memory. It also allows loading DOS to the upper memory block. Nowadays most of the programs require XMS (e.g., MS-Windows).
Extension: A suffix added to a filename. An extension may be any three legal filename characters.
Fanfold paper: A continuous sheet of paper whose pages are folded in accordion-style and separated by perforations. Long documents can be printed on it without inserting paper manually.
Field: The smallest independent item of a record in a database.
File: A collection of logically related records or data treated as a single item. A file is a record where data is stored on a disk or diskette, so it can be used later.
Filename: The sequence of alphanumeric characters assigned by a user to identify a file which can be read by both the computer and the user. On PCs, a file name has a maximum length of eight alphanumeric characters and an extension of three characters can be added to it.
Flexible disk: See diskette.
Floppy disk: See diskette.
Font: A complete set of letters, numerals, and symbols of the same typestyle of a given typeface. Examples of typefaces are TimesRoman and Helvetica. Examples of fonts are TimesRoman Italic, TimesRoman Bold, and TimesRoman Bold Italic.
Foreground processing: Top-priority processing; it has priority over background (lower-priority) processing.
Format: The way text appears on a page. There are three types of formats: font and font size (character formats); paragraph alignment (paragraph formats); and overall page design (division formats).
Formatting: (1) Preparing the diskette for writing data to it. (2) Designing the appearance of text in a document.
Formfeed: Automatically advances a roll of fanfold paper to the top of the next page.
FORTRAN: (Formula Translation): A widely used high-level programming language suitable to solve problems that can be expressed in algebraic formulas. It is generally used in scientific applications.
Function key: A key that causes a computer to perform a function (such as clearing the screen) or execute a program.
Graphics: Usage of lines and figures to display data, in contrast to the use of printed characters. See bit-map graphics.
Hardcopy: Output something in a permanent form (usually on paper or paper tape) rather than in temporary form as on a CRT or visual display.
Hard disk: A disk that is not flexible, such as a Winchester disk. It is more expensive than a diskette but is capable of storing much more data. See disk and Winchester disk.
Hardware: The physical equipment that makes up a computer system.
Hardwired: Refers to a permanent (opposite of a switched connection) physical connection between two points in an electrical circuit or between two devices linked by a communications line. When using a personal computer, local connections are typically hard-wired, whereas all connections through a modem are switched because they use telephone lines.
Head: A component that reads, writes or erases data on a storage medium such as a diskette or disk.
Help service: Messages displayed on the video screen that provide information on how to use applications and other system services.
IC: See integrated circuit.
Impact printer: A printer that forms characters on paper by striking an inked ribbon with a character-forming element.
Import: To read data (texts, numbers, images) into an application program from files generated by an other program. There are common file formats and converters to make it easier. See Export.
Index file: A table extracted from a database. It contains the localization of the given key expressions in the database to accelerate searching.
Ink jet printer: A type of desktop printer that prints by sparing ink on paper. Ink jet printers can print in black and white and color in varying resolution.
Instruction: A command that tells the computer what operation to perform next.
Integrated circuit (IC): A complex electronic circuit on a single chip.
Interactive: Capable of carrying on a dialogue through the keyboard with the user, rather than simply responding to commands.
Interface: An electronic circuit that connects an external device, such as a printer, to a computer.
Job: A task (program) for a computer to execute, such as reading a disk or printing a file.
K: The symbol for the quantity 210 or 1024. The K is uppercase to distinguish it from lower-case k, which is a Standard International Unit for "kilo," or 1,000.
Keyboard: The set of keys on a terminal that allows alphanumeric characters or symbols to be transmitted when keys are depressed. It inputs text and instructions to the computer
Kbyte (KB): 1,024 bytes.
LAN (Local Area Network): Computer network of small distances (max. 5 km). It is typically used inside an institution (hospital, university, etc.). See also Arcnet, Ethernet, Novell, UNIX.
Laser printer: High resolution printer based on the principle of electrostatic copiers (Xerox machines). The Hewlett-Packard printers are regarded as world standards (HP LaserJet+, II, III, IV). The resolution is between 300 and 600 dot per inch.
Laptop computer: A portable (5-7 kg) computer with liquid crystal monitor.
Large-scale integration (LSI): Combination of about 1,000 to 10,000 circuits on a single chip. Typical examples of LSI circuits are memory chips, microprocessors, calculator chips and watch chips.
Letter-quality printer: The printer used to produce final copies of documents. It provides a printing quality of a typewriter.
Lineprinter: High-speed printer that prints an entire line of characters at a time.
List processing: The word processing application that permits many copies of a form document to be produced, with certain information changing from one copy to the next (e.g., the production of personalized form letters).
Local: Hardwired connection of a computer to another computer, terminal, or peripheral device such as in a local area network. See remote.
Local Area Network: See LAN.
LSI: See large-scale integration.
Macro: A series of key-strokes. Allow the user to save keystrokes needed to perform a specific operation, and then initiate them by pressing a key.
Magnetic tape: Magnetic tape used as mass storage media. Since the data stored on magnetic tape can only be accessed serially, it is not practical for use with personal computers. However, it is often used as a back up device.
Mainframe: A computer that is physically large and provides the capability to perform applications requiring large amounts of data (e.g., for large-scale payroll system). These computers are much more expensive than microcomputers or minicomputers.
Main memory: See memory
Mass storage: A device like a disk or magnetic tape that can store large amounts of data readily accessible to the central processing unit.
Mbyte (MB): 1,048,576 (1020) bytes, 1024 (1010) Kbytes.
Medium: The physical substance upon which data is recorded, for example, magnetic disks, magnetic tape or punched cards.
Memory: (1) The main high-speed storage area in a computer where instructions of a program can be found temporarily. (2) A device in which data can be stored and from which it can later be retrieved.
Menu: A list of options from which the user selects an action to be performed by typing a letter or by positioning the cursor by using the arrow keys or the mouse.
Menu-driven: A computer system that primarily uses menus as its user interface rather than a command language.
Microcomputer: A computer which is physically very small - it can fit on or under a desk - and which is based on large-scale integration (LSI) circuitry. It is usually the least expensive of the computer types.
Microprocessor: A single-chip central processing unit incorporating LSI technology.
Minicomputer: A type of computer whose physical size is usually smaller than a mainframe. In general, its performance exceeds that of microcomputers. Since minicomputers are more modular than mainframes, they can be configured to provide better price/performance systems. The most popular mini is the VAX (manufactured by the Digital Equipment Corporation).
Mnemonic: A short, easy-to-remember name or abbreviation. Many commands in programming languages are mnemonics.
Modem (Modulator/Demodulator): A device that converts computer signals (data) into high-frequency communications signals, and vice versa. These high-frequency signals can then be sent over telephone lines.
Monitor (hardware): A television-like device that can be used as an output display See also cathode-ray tube and display screen.
Monitor (software): Part of the operating system. Allow the user to enter programs and data into memory. Run programs and check the registers of the processor. On IBM PCs its name is DEBUG.
MOS: Metal-oxide semiconductor, the most common form of LSI technology.
Mother board: The base electronic circuit board of the computer which contains the microprocessor, the ROM, the RAM and expansion slots for the disk drivers, I/O ports, graphics card, etc.
Multi-copy form: A preprinted, multiple form that contains carbon paper between the pages (e.g., tax forms and credit card receipts).
Multi-key sort: Using more than one parameter to qualify a record for inclusion in a specified group or to order a set of records.
Multi-processing: Execution of two or more computer programs by a computer which has only one processor.
Multi-programming: A scheduling technique that allows more than one job to be in an executable state at a time. Thus, even with one CPU, more than one program can appear to be running at a time because the CPU is giving small slices of its time to each executable program. See multi-tasking.
Multi-tasking: The execution of several tasks "at the same time without having to complete one before starting another Although computers can perform only one task at a time, the speed at which a computer operates is so fast that it appears as though several tasks are being performed simultaneously. See multi-programming.
Network: A group of computers that are connected to each other by communications lines to share information and resources. See computer network.
Nonvolatile memory: Memory that does not lose its contents when a processor's power supply is shut off or disrupted.
Novell NetWare: The most popular network operating system of IBM PCs. It runs on a PC equipped with a high capacity hard disk. The network can be either Arcnet or Ethernet. It mainly ensures file-server functions: the terminals can share the disk of the server, but the programs should be loaded into the terminal's memory before starting them. Therefore, there is high degree of data transfer in the system which limits the performance.
Optical Character Recognition (OCR): OCR programs can recognize the characters on a scanned image and store the text in the form of ASCII codes.
On-line: Directly under the control of the computer; data is introduced into the CPU immediately
Operating system: A collection of computer programs that controls the overall operation of a computer and performs tasks as assigning places in memory to programs and data, processing interrupts, scheduling jobs and controlling the overall input/output flow of the system.
Option module: A plug-in electronic circuit. Can be inserted into a free slot of the computer. See board.
Parallel transmission: Sending more than one bit at a time. See serial transmission.
Parity: A one-extra-bit code used to detect recording or transmission errors by making the total number of "l" bits in a unit of data - including the parity bit itself - odd or even.
Peripheral: A device that is external to the CPU and main memory, e.g., printer, modem, or terminal but connected to it by appropriate electrical connections.
Pica: A unit of measure used in typography. There are twelve points in a pica and six picas in an inch. See also Point, Pitch.
Pitch: A horizontal measure of the number of characters per inch (cpi). Most typewriters and printers use 10-pitch (10 characters per inch) or 12-pitch (12 character per inch).
Pixels (Picture elements): Locations on a display screen that are used to form images on the screen. For graphics displays, screens with more pixels generally provide higher resolution. See bit-map graphics.
Point: A unit of measure used in typography. There are 12 points in a pica and 72 points in an inch.
Port: Physical area of the connection of a communications line. This line can be between the CPU and anything external to it, such as a printer, another computer, a modem, or another communication line.
PostScript: A page-description language, developed by Adobe Systems Inc., that is used by high resolution printers.
Power supply: A transistor switch that converts AC into DC; supplies components such as integrated circuits, monitors and keyboards; and steps down the power supplied to some components.
Printer: The device that produces a paper copy of a document (hard copy output). There are two types: draft-quality and letter-quality printers. Unlike a terminal, there is virtually no communication from printer to CPU.
Printhead: The element in a printer that forms a printed character.
Print queue: See Spooler.
Printwheel: See daisywheel.
Printout: An informal expression referring to almost anything printed by a computer peripheral device; any computer-generated hard copy.
Program: The complete sequence of instructions and routines needed to solve a problem or to execute directions on a computer. The machine code program files have the extension COM (COMmand file) or EXE (EXEcutable program).
Program disk: A disk containing the instructions of a program.
Programming language: The words, mnemonics and/or symbols, along with the specific rules allowed in constructing computer programs.
Protocol: Complex entirety of rules for the communication between two computer systems.
RAM (Random Access Memory): Memory that can both be read and written into (i.e., altered) during normal operation. RAM is the type of memory used in most computers to store the instructions of programs currently running.
Real-time: A function (data access, display, etc.) performed during the course of a process, without interpreting it. It refers to computer systems or programs that performs a computation meanwhile a physical process transpires. The results can be recorded or used to guide the physical process, e.g., computers that guide airplane landings.
Record: A collection of related data items.
Remote: Not hard-wired; communicating via switched lines such as telephone lines. Usually refer to peripheral devices (e.g., printers, video terminals) that are located in a different location than the CPU.
Resolution: (1) Rate of dots per inch (dpi) scanned or printed. The greater the number of dpi, more detail is visible in the image or printout. Recent, equipment can work at 300-600 dpi. (2) The resolution of screens and graphic cards are given by the number of horizontal and vertical pixels. The highest SVGA resolution is 1280x1024.
[pic]
Understanding the technology...
Reverse video: A feature on a display unit that produces the opposite combination of characters and background from that which is usually employed, i.e. white characters on a black screen, if having black characters on a white screen is normal.
ROM (Read Only Memory): Memory containing fixed data or instructions that is permanently loaded during the manufacturing process. A computer can use the data in the ROM but cannot change it.
Scanner: An input device that reads printed or typed information directly into your PC. Handy scanners can scan only a narrow stripe (10 cm), the larger models can read A/4 or A/3 sheets.
Screen: (1) The display surface of a video monitor (2) The pattern or information displayed on the screen.
SCSI (Small Computer System Interface): An interface that allows hard disks and other high-performance peripherals (e.g., scanners, CD-ROM drives) to be attached to Macintosh, PC and UNIX computer systems.
Self test: A procedure where a program or peripheral checks its own operation.
Sequential access: Refers to devices, like magnetic tape, from which data or instructions can be retrieved only by passing through all locations between the one currently being accessed and the desired one.
Serial access: See sequential access.
Serial transmission: Sending one bit at a time. See parallel transmission.
Single-thread: Refers to a simple operating system that executes any given task from beginning to end without interruption, opposite of the multi-tasking system.
Softcopy: Alphanumeric or graphical data (or both) presented in temporary form, such as on a video screen.
Software: The tasks or programs that makes the computer perform a particular function.
Sort: Rearranging the records in a file so that the order is convenient to the user.
Spooler: A program that sends files to the printer. The spooler hold files in the print queue, then sends another one when the printer is ready. The spooler allows you to continue working on another files while a file is being printed. The networks use similar method for printing on a central printer.
Storage unit: Where documents can be saved for later use. Usually a disk or diskette.
String: Series of alphanumeric characters.
System: A combination of software and hardware that performs specific processing operations.
System board: See mother board.
Task: A program under execution.
Terminal: An input/output device used to enter data into a computer and record the output. Terminals are divided into two categories: hard copy (e.g., printers) and soft copy (e.g., video terminals).
Terminal emulation: A communication method in which a terminal acts as a terminal of a different design so that it can be used on various systems. For example, PCs can be used as UNIX terminals by using a terminal emulator software.
Thermal transfer printer: A type of printer that prints by bonding pigment or paper with heat. These printers generally can print in higher resolution than ink jet printers.
TIFF (Tag Image File Format): An industrial standard of image file format supported by many applications. These files have TIF extension.
Timesharing: Providing service to many users by working on each application by switching between them in predefined intervals.
Track: The portion of a moving storage medium, such as a disk or tape, that is accessible to a given read/write head position.
Tractorfeed: The mechanical apparatus used to move paper through a printer The roller that moves the paper has sprockets on each end. They fit into the fanfold paper's matching holes.
Turnkey system: A computer that is ready to be used without adding any hardware or software; it is ready-made for a given task.
Typeface: See font.
UMB: See upper memory block.
Upgrade: To expand your personal computer or software as new versions are developed, or to enhance existing features.
Upgrading: If you have a registered software the manufacturer sales you the new version for a reduced price.
Upper Memory Block (UMB): The blocks of the memory area between 640 K and 1 M in ATs. See extended memory.
Video monitor: See monitor (hardware).
Video terminal: A terminal that displays data on a CRT
Volatile memory: Memory that loses its contents when power is removed unless battery back up is available. See core and non-volatile memory.
VT: Video terminal. The common trademarked name of DIGITAL's VT family of video terminals.
Winchester disk: A hard disk permanently sealed in a drive unit to prevent contamination of the heads; this virtually eliminates the need for adjustment by service personnel. The disk is capable of storing larger amounts of data than a diskette.
Window: An area on the screen where you are running an application (e.g., in Microsoft Windows) or a file is being shown.
Windows: Graphic operating system of the Microsoft Corp.
Word: The highest number of bits a computer can handle during operation. Usually subdivided into bytes.
Word processing system: A system that processes text, performing functions as paragraphing, paging, left and right justification, rearrangement of lines and printing the text.
Word-wrapping: The automatic shifting of words of a line to left, when the length of the line exceeds the actual paragraph (screen) width.
Workstation: High performance microcomputer (in UNIX systems). Workstations with a large hard disk can be used as servers, diskless workstations can be used as intelligent terminals.
WYSIWYG (What You See Is What You Get): Same image will appear on the screen and the printer.
XMS: See extended memory.
X-terminal: High resolution graphic terminal used in UNIX systems.
Zoom: Enlarging or reducing the size of a window.
1.8 The Hungarian Keyboard (Used at the DOTE)
+-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
¦Í¦ ¦'¦ ¦"¦ ¦+¦ ¦!¦ ¦%¦ ¦&¦ ¦/¦ ¦(¦ ¦)¦ ¦=¦ ¦Ö¦ ¦Ü¦ ¦Ó¦ ¦B¦
¦í¦ ¦1¦ ¦2¦ ¦3¦ ¦4¦ ¦5¦ ¦6¦ ¦7¦ ¦8¦ ¦9¦ ¦0¦ ¦ö¦ ¦ü¦ ¦ó¦ ¦S¦
+-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
+---+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +---+
¦Tab¦ ¦Q¦ ¦W¦ ¦E¦ ¦R¦ ¦T¦ ¦Y¦ ¦U¦ ¦I¦ ¦O¦ ¦P¦ ¦U¦ ¦Ö¦ ¦ ¦
¦ ¦ ¦q¦ ¦w¦ ¦e¦ ¦r¦ ¦t¦ ¦y¦ ¦u¦ ¦i¦ ¦o¦ ¦p¦ ¦ú¦ ¦ö¦ ¦ ¦
+---+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ ¦ ¦
+-----+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ ¦
¦Caps ¦ ¦A¦ ¦S¦ ¦D¦ ¦F¦ ¦G¦ ¦H¦ ¦J¦ ¦K¦ ¦L¦ ¦É¦ ¦Â¦ ¦Enter¦
¦Lock ¦ ¦a¦ ¦s¦ ¦d¦ ¦f¦ ¦g¦ ¦h¦ ¦j¦ ¦k¦ ¦l¦ ¦é¦ ¦á¦ ¦ ¦
+-----+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-----+
+-------+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-------+
¦ Shift ¦ ¦Z¦ ¦X¦ ¦C¦ ¦V¦ ¦B¦ ¦N¦ ¦M¦ ¦;¦ ¦:¦ ¦Ü¦ ¦ Shift ¦
¦ ¦ ¦z¦ ¦x¦ ¦c¦ ¦v¦ ¦b¦ ¦n¦ ¦m¦ ¦,¦ ¦.¦ ¦ü¦ ¦ ¦
+-------+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-------+
+-----+ +-----+ +-------------------+ +-----+ +-----+
¦Ctrl ¦ ¦ Alt ¦ ¦ Szóköz ¦ ¦ Alt ¦ ¦Ctrl ¦
¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦
+-----+ +-----+ +-------------------+ +-----+ +-----+
1.9 The IBM Character Set
[pic]
[pic]
[pic]
[pic]
-----------------------
[1] It is very irritating that although our machines usually contains 4-16 Mbyte of RAM, accessing the memory areas above 1 Mbyte is very difficult. We need a special driver program to do this and there are two different standards for handling this memory (EMS and XMS). Formerly the new programs were expected to run on the older (XT) machines as well and that was a strong limitation in development. Only the latest operating systems (Windows, OS2) can make the most of the 32 bit bus architecture.
[2] These SVGA cards need 2 Mbyte of RAM on board, fast bus access (at least VLB=Vesa Local Bus), and expensive high resolution monitors.
[3] You can start the setup program by holding the or keys pressed while the machine is starting. It is inadvisable to use this program for a beginner. If you are a more advanced user you can change the major settings of your system (type of the floppy disk drives, type of the hard disk drive with autodetection, password checking, etc.) The way of usage is written in the mother board manual but if you do not understand anything call a specialist.
[4] It is an NTSC standard (American, Japanese) video signal with 60 Hz frequency.
[5] The quality of the monitors depends on the physical pixel size, mass-produced monitors have a 35 mm pixel size, better screens are built up from 28 mm pixels. It is worth buying NI (Non Interlaced) and LR (Low Radiation) monitors because they do not constrain your eyes. The diameter of the normal screens is 14 “, but you need larger (17-20 “) monitors for speccial applications such as desktop publishing, image processing, etc.
[6] The boot sector of the floppy or hard disks is the favorite target of the viruses. You can kill them with special programs or you can install a virus protection system that checks the new programs.
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related searches
- 1 or 2 374 374 1 0 0 0 1 168 1 1 default username and password
- 1 or 3 374 374 1 0 0 0 1 168 1 1 default username and password
- 1 or 2 711 711 1 0 0 0 1 168 1 1 default username and password
- 1 or 3 711 711 1 0 0 0 1 168 1 1 default username and password
- 1 or 2 693 693 1 0 0 0 1 168 1 1 default username and password
- 1 or 3 693 693 1 0 0 0 1 168 1 1 default username and password
- 1 or 2 593 593 1 0 0 0 1 or 2dvchrbu 168 1 1 default username and password
- 1 or 3 593 593 1 0 0 0 1 or 2dvchrbu 168 1 1 default username and password
- 1 or 2 910 910 1 0 0 0 1 168 1 1 default username and password
- 1 or 3 910 910 1 0 0 0 1 168 1 1 default username and password
- 192 1 or 2 33 33 1 0 0 0 1 1 1 default username and password
- 1 or 2 364 364 1 0 0 0 1 168 1 1 admin username and password