Computer Systems

This Module

Components Home PC Inputs Processor Memory Motherboards Auxiliary Storage Outputs

Components

All computers no matter what size have the following parts

– Input devices– Main Memory– CPU (Central Processing Unit)– Output devices– Storage devices

Components

This diagram shows how each component links into the processor

ProcessorInput

DevicesOutputDevices

Auxiliary Storage

Main Memory

Inputs

Devices that allows data to enter the computer.

Mouse / Roller Ball Keyboard Digitiser Scanner Joystick / Pad / Steering Wheel Digital Camera Microphone

Processor

The brain of the system. Processor power measured two ways.

– Speed of Processor.– Type of processor.

How does it work– Moves data from Inputs to memory.– Processes data in memory.– Moves data from memory to outputs.

Integrated circuit (Chip) Microcomputer CPU sometimes called

microprocessor.

Processor Architecture

Lots of different types of processor Two Main families in home computers

– Motorola, used in Macs– Intel, used in PCs

Intel processors– Pentium 4, Pentium III, II, Pentium, Celeron– AMD?

Speed 100Mhz Pentium – 2Ghz Pentium 4

Cost– Pentium 4 1.5 Ghz £150, 2 Ghz £500

Main Memory

Instructions (program) and Data (Documents) are held in main memory.

Memory split into little units called bytes.– One byte holds one character, or a tiny part of a

picture or sound file.

Amount in PC grown each year from a few K to 640K to 2Mb, 4Mb, 8Mb, 16Mb, 32Mb,64Mb, 128Mb etc

Measuring Memory

1 Kilobyte (Kb) = 1,000 bytes (1024)

1 Megabyte (Mb) = 1,000,000 (1 million) bytes

1 Gigabyte (Gb) = 1,000,000,000 (1 billion) bytes

1 Terabyte (Tb) = 1,000,000,000,000 (1 trillion) bytes

RAM and ROM

Two kinds of memory Ram (Random Access Memory).

– Standard type of memory used a previous pages.

– Volatile – loses data when power removed.

ROM (Read Only Memory)– Non-volatile– Bios (hardware set-up)– PROM, EPROM,EEPROM

Motherboards

All parts connect via this Consists of

– Slots Memory PCI AGP Ports

– Connectors Bios Processor Disks Power

– Ports

Plus Circuitry to control the movement of data.

Circuitry called the chipset of the motherboard

New processors need new chipsets

Auxiliary Storage

Because RAM is volatile, a computer needs something to store its programs and data when it is switched off or when it needs to load a different set of instructions or data.

– Hard disk 10Mb, 100Mb, 1Gb, 10Gb, 100Gb etc

– Floppy Disk, 1.4 Mb– CD’s 650Mb– Zip/Iomega disks 100Mb– DVD RAM

Measuring Storage

Storage can be measured several ways Speed

– How fast data can be accessed 5 – 10 ms seek time

Size– How much data can be stored

20Gb – 81 Gb

Cost– Slow 40Gb = £100, Fast 36Gb = £300

Type– Read capability– Write capability

Output Devices

Devices that allows data to be used by an end user

Printers– Laser– Inkjet– Impact– Measured by resolution (DPI)

Screens– Size– Colour– Resolution (pixels)– Refresh rate (interlaced / non-interlaced

Speakers Others

Any Questions