Homework

Question 1

• CD ROM disk is an example of an optical storage device.

• CD ROM disks can only be used to read information stored on them. The user cannot save data to a CD ROM disk.

• Encyclopaedia is an example.

B) A floppy disk can store data and write data.

C) CONTROL UNIT - controls the flow of information. It fetches instructions from memory and decodes them into commands the computer can understand.

It controls the timing so everything happens in the correct order at the correct time.

ALU - handles the calculations and logical comparisons.

D) (i)Operating System - Another unit!

(ii) RAM can be edited and changed. Can be written to and read from.

Laser Printer

• Operates using a laser beam

• Very expensive to buy and run

• Fast output

• High quality printouts

• Quiet in sound

Ink Jet Printer

• Operates by spraying ink onto the paper

• High quality printouts

• Cheaper to buy than laser

• Cheaper to refill

• Quiet in sound

Mouse

Hand held device used for selecting icons and menus from the GUI

When the mouse is moved it sends a signal back to the computer.

3 types are wireless, optical and multi-button.

Cheap to buy from £3-£16

Touch Pad

Touch sensitive pad used as a pointing device for selection icons and menus from a WIMP environment.

This is done by moving your finger along the pad and double clicking(tapping) to open icons.

Used on laptops

Easy to use for experienced users. Unsuitable for high definition graphics.

Interface

In order to connect input, output and backing storage devices to the computer an interface is required.

Interface is required because there are different characteristics between peripherals and the processor.

Types of interface:

• USB

• ATA/IDE

• Serial

• SCSI

• Parallel

• Firewire

• PCI

UBS (Universal Serial Bus)

Allows a very fast communication between devices. A desktop computer comes with about 2 USB port. However, a hub can be connected allowing many devices to connect.

Detected as soon as it is plugged into the computer.

Data transfer of about 12Mb per second.

ATA/IDE (Advanced Technology Attachment/Integrated Drive Electronics)Used for Hard Disk or CD/DVD ROM drives. Data transfer rate of about 830 Mb per second.

ATA SOCKET ATA CABLE

Serial ATA CABLE

Serial

A serial port is an interface on a computer system with which information is transferred in or out one bit at a time.

Used to connect monitors, printers and Interactive whiteboards.

SCSI (Small Computer System Interface)

Allows eight peripheral devices to be connected to the computer in a daisy chain fashion.

This is located inside the computer.

Useful when combining scanner, CD-ROM drives, printers etc.

Data transfer of about 4Mb per second – 80Mb per second.

Parallel Interface

A parallel interface for connecting an external device such as a printer.

Most personal computers have both a parallel port and at least one serial port.

On PCs, the parallel port uses a 25-pin connector and is used to connect printers or scanners.

FirewireA very fast external bus standard that supports data transfer rates of up to 400Mbps and 800Mbps.

FireWire can be considered a successor technology to the obsolescent SCSI Parallel Interface.

Used for connecting digital cameras and iPods.

PCI (Peripheral Component Interconnect )

Expansion cards that are fitted inside a computer.

Used for graphics, sound, Ethernet and modem cards.

Modem

The word "modem" is a contraction of the words modulator-demodulator. A modem is typically used to send digital data over a phone line.

The sending modem modulates the data into a signal that is compatible with the phone line, and the receiving modem demodulates the signal back into digital data.

Wireless modems convert digital data into radio signals and back.

MODEM

Class Questions

1. Why is a keyboard sometimes called a QWERTY keyboard?

2. What does OCR stand for?3. State two advantages that an LCD panel has over a CRT

monitor.4. Write a helpful of helpful advice to a friend who was

considering purchases of a:1. Scanner2. Digital Camera

Functions of an Interface

Data Format Conversion:

Changing data into a form that can be processed.

Serial

-sending single bit in a serial format requiring only 2 lines

- good for long distance

-secure

Parallel

-sending groups of bits on separate data lines requiring multiples of 8 lines

-Faster speed

-Better for shorter distance

-Risk of data collision

Serial / Parallel:

Functions of an InterfaceAnalogue to Digital Conversion

ANALOGUE

Represented by a wave

Infinite readings

DIGITAL

A step signal representing two state reading 0 or 1

Conversion required because computers don’t understand analogue readings so measures of temperature or sound etc.. Require to be converted into digital for storage and use by computer programs.

Types of converters are ADC or DAC

Functions of an Interface

Voltage Conversion:

Where there is a difference in voltage settings this difference must be compensated in order for the mother board and devices to work together.

Usually around 5v

Protocols:

A protocol is a procedure of operation, in some devices the procedure is different and again these differences need to be compensated for smooth running of peripherals with the computer.

Protocol ExampleParity check: When sending bits these need to

be received and checked for accuracy and security, two examples of how this is done is using a parity check either set to odd or even.

Even parity – the no. of 1’s is an even number

Odd parity – the no. of 1’1 is an odd number

The parity bit makes the signal either odd or even

Functions of an Interface

Buffering: Temporary area of memory for holding data in transit between a computer and peripheral. This will compensate for differences in working speeds.

Spooler: A program using fast backing storage to temporarily hold print jobs. As in the buffer this will compensate for operational differences particularly speed.

Data is sent to backing store until printer is ready, freeing up processor for user to continue. This is known as background printing.

Advantage of spooling is the large capacity of backing storage

Functions of an Interface

International Standards:

The use of standards means that computers can be used with a variety of peripherals using the same standards

Solid State Storage

1. What is solid state memory?

2. Give two examples of flash memory.

3. Why do flash card readers often have more than one slot?

4. Discuss the following features of flash storage:

Size, power consumption, reliability, capacity

Development Trends

Investigate and report on the following trends:

• Backing Storage

• Wireless technology

• Mobile phones

Practical Task

Investigate and write a report summarising hardware, software and cost factors involved in producing one of the following products::

Multimedia Catalague

Business Website

Include in your report resolution, capacity, speed and cost of each piece of hardware you identify.

NB: You must not exceed £800