Computer Basics – Study Notes



Computer Basics – Study Notes – Grade 10

IPO

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← Computers solve problems based on the information we give them; this information is called INPUT

← The unit of the computer responsible for gathering the input is called the Input Unit

← After the computer has the information, it has to do work to solve the problem; this stage is called PROCESSING

← The unit of the computer responsible for processing is called the Central Processing Unit or the CPU

← The computer needs to output the results of the work. This stage is called OUTPUT

← The unit of the computer responsible for output is called the Output Unit

The Computer System

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Hardware and Software

← In a computer system, hardware consists of the physical components you can touch

← Examples: keyboard, monitor, processor, hard disk, memory

← Another important part of the computer that you can’t touch is called software

← Software is the set of instructions that controls the hardware

Programs

← Each complete set of instructions with a specific purpose is called a program

← Examples of programs…

← Microsoft Windows, MS Office, Video Games, MSN Messenger, viruses, hardware drivers

Memory Unit

← To run or execute a program means that the set of instructions that makes up the program have to be followed by the CPU

← A program is like a recipe; when a computer runs a program, it is like a person following a recipe

← While a computer is running a program, the instructions for that program have to be stored in memory which the processor can access

← RAM stands for Random Access Memory and is sometimes called primary memory or main memory

← Because the CPU requires RAM to function in a meaningful way

← RAM or main memory is essential to a computer, but tends to be expensive

Secondary Memory

← Larger, cheaper secondary memory can be used to store large amounts of data that are accessed infrequently

← Examples of secondary storage…

← Hard disks, CD-ROMs, flash/USB drives, floppy disks

CPU

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← All instructions in a computer are either control instructions or arithmetic/logic instructions

← So each instruction is either handled by the ALU or the control unit

ALU

← Most computer operations are executed in the arithmetic and logic unit or ALU

← The ALU is responsible for performing mathematical as well as logical operations

← Mathematical operations include addition, subtraction, division, multiplication, modulo

← Logical operations include evaluating conditions

Control Unit

← The control unit is the nerve centre of the computer

← It handles instructions dealing with control signals

← You can think of the control unit as a manager that controls information flow in a computer

Computer Performance

← The most important measure of a computer is how quickly it can execute programs

← The processor is controlled by a clock where one basic instruction is completed in one clock cycle

← So if a clock cycle is shorter, then the computer takes less time to execute a basic instruction

← Let P be the length of one clock cycle

← The measure of a computer is the clock rate, R = 1/ P

← Thus, when P is small, R is large

← R is measured in cycles per second or Hertz (Hz)

← Computers today have clock rates in the billions

← The term “million” is denoted by the prefix Mega (M) and “billion” by Giga (G)

← So a 500 MHz processor operates at 500 million cycles per second

← A 2 GHz processor operates at 2 billion cycles per second

← This is the number of basic instructions the processor can go through in 1 second

Understanding how to buy a computer in modern times project

← L2 Cache

← Different processor families (Intel Core, Pentium, Celeron, AMD, etc.)

← What to consider when buying a computer

Sample Problems for Computer Performance

1) If the processor in your computer is 2 GHz, what is P (the length of one clock cycle)?

2) If the processor in your computer has a clock cycle length of P = 0.8 nanoseconds (0.0000000008 seconds), what is the clock rate of your computer? (in other words, how fast is your processor?)

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Input Unit

Processing

Unit

Output Unit

CPU

Input Unit

Output Unit

Memory (RAM)

Unit

CPU

Arithmetic and

Logic (ALU)

Control

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