Chapter 5 The System Unit of a Computer System



Chapter 5 The System Unit of a Computer System

1. Transistor, integrated circuit, ALU, CPU, motherboard, system unit, hardware, computer

2. Microprocessor, RAM

3. ALU: (b), (e)

CU: (a), (c), (d)

5. (a), (d), (e)

6. (a) 2 × 108 Hz

(b) 2.4 × 109 Hz

7. Approximate Actual size

(a) 256,000 bytes 262,144 bytes

(b) 1.28 × 108 bytes 134,217,728 bytes

(c) 5.12 × 108 bytes 536,870,912 bytes

(d) 2.0 × 109 bytes 2,147,483,648 bytes

(b) control unit

(c) arithmetic and logic unit

(d) random access memory

(e) read only memory

(f) megahertz

(g) gigabyte

9. RAM ROM

(a) IC IC

(b) data/instructions being processed system program and data

(c) volatile non-volatile

(d) yes; memory size can be increased no

(e) same same

(f) read and write read only

10. (a) CMOS

(b) ROM

(c) RAM

(d) RAM

11. (a) Data bus

(b) It means that there are 64 bits of data transmitted from one location to another at a time.

12. (a) Memory access is direct. An address is needed to access a piece of information in the memory

(b) Bi-directional

13. (a) A system bus connects between the CPU and memory. A peripheral bus connects the memory and peripheral devices.

(b) PCI, USB, ISA, SCSI, AGP

14. (a) 1. both connected to the peripheral bus

2. both connected to peripheral devices

(b) Port: USB port, serial port, parallel port, SCSI port, keyboard and mouse port, IEEE 1394 port, IrDA port.

Interface card: sound card, VGA card, network interface card (NIC), modem card

Chapter 6 Input and Output Devices

1. Main memory

2. (a) The devices is connected directly to the mother board of the computer and is always turned on. Data is input directly to the memory.

(b) i) Bitmap graphic files

ii) A keyboard inputs the keystrokes directly onto the memory of a computer. This is known as online input. A digital camera, however, does not input directly to the memory of a computer. This is known as offline input.

3.

|Advantages |Disadvantages |

|(a) |• no cluttering of wire |• require battery |

| |• can use at a larger distance | |

|(b) |• does not require space for keyboard |• not 100% correct |

| |• no moving parts |• not suitable for input large amount of data |

|(c) |• less hand movement |• not 100% correct |

| | |• require hand movement when incorrect input occurs |

4. 1. Kiosk

2. Handheld computers

3. Tablet PC

5. Touchpad, pointing sticks

6. (a) Customer’s account number, invoice number and amount due

(b) They should be printed in OCR characters, which are then read by an OCR reader. Alternatively, in bar code. This eliminates error in processing and speed up input.

7. (a) In case the bar code reader fails to read the code

(b) Faster, more accurate and error free

8. OCR reader, scanner with OCR system, voice input, keyboard, touch screen with handwriting recognition

9. (a) It means that the contents on the medium can be overwritten

(b) 1. no film cost

2. can be transmitted in electronic form easily and at low cost

3. result can be viewed instantly

4. allow choice of photo before printing

5. easy and unified management using computer

10. (a) Microphone, speaker, Web cam (or DV camera), visual display unit

(b) The computer needs to be able to access the Internet/network. Since video involves a lot of data, the computer must have has large enough memory and fast enough CPU to handle the video as well as sound.

11. (a) Processing unit and main memory

(b) It can change the stored content, for example, deducting the deposit It can be programmed to self-destruct

12. (a) Authenticating system that detects fingerprint, face geometry, hand geometry, voice, iris pattern.

(b) Eliminate fraud using stolen cards

13. (a) Hardcopies are printed document that can be carried independent of machine. Softcopies are output in electronic forms. Hardcopies are more permanent.

(b) Hardcopies: printer

Softcopies: monitor, speaker

14. (a) An impact printer consists of a hammer that strikes an inked ribbon to produce output on paper. A non-impact printer does not have hammers. An impact printer is noisy and slow.

(b) Impact printer: dot-matrix; non-impact printer: inkjet, laser and thermal printer

15. (a) Quality is measured by print resolution or dpi.

(b) The two are independent of each other.

(c) Inkjet printer will be blurred by water/ the ink on the paper from inkjet printer needs time to dry.

(d) Thermal printer

Chapter 7 Secondary Storage

1. (a) Memory are more expensive.

(b) Data access in memory is faster.

(c) Secondary storage provides a higher storage.

(d) Memory is volatile.

2. 1. Data stored in the RAM of the main memory are lost when the machine is powered off, that is, RAM volatile;

2. The memory size is limited. It may not be possible to hold all the data in main memory at the same time because the size of a file might be greater than the memory size; and

3. Main memory is more expensive.

3. (a) Hard disk, floppy disk, CD-ROM

(b) Speed of data access in descending order: hard disk, CD-ROM, floppy disk

Cost in descending order: hard disk, CD-ROM, floppy disk

Storage capacity in descending order: hard disk, CD-ROM, floppy disk

4. (a) 1. Damage of files due to head crash.

2. Damage of files due to virus.

(b) Tape, CD-R or CD-RW etc.

(c) OS, system software, application program

5. (a) Backup is needed; Data transfer is needed.

(b) High speed, can be overwritten

(c) OS, system software, application program, driver programs

(d) 1. Using portable storage medium

2. Network/Internet

6.

|Advantages |Disadvantages |

|(a) |• can be used without a computer |• slow in looking up a word |

| | |• bulky |

| | |• without multimedia features |

|(b) |• has multimedia features |• must used with a computer |

| |• can be used with most computers | |

| |• at lower cost | |

|(c) |• portable |• must used with the electronic device |

| |• can be used without a computer |• more expensive |

7. (a) A floppy disk has only 1.44MB storage. A multimedia file, e.g. video file, is normally much larger than this.

(b) 521

(c) Special drives are needed to read/write a high density disk.

8. (a) 150 MB

(b) 1

9. (a) Tape is sequential access. Search is done from the beginning of the tape.

(b) Low cost, large capacity

(c) A CD-R cannot be overwritten

(d) When a data file is opened by some users, it is locked and cannot be accessed by the backup software

10. (a) He should copy the file and rename it.

(b) When a new file is saved to a CD-R, the existing files would be invisible.

(c) CD-RW, high storage density disk.

11. (a) Hard disk, floppy drive, DVD-ROM drive

(b) Floppy drive, DVD-ROM drive, hard disk, RAM

(c) Increase the memory capacity.

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