UNIT 2.1Lucy-Jane Constable

SYSTEM UNIT COMPONENTS

PROCESSOR A processor is an electronic circuit that can computer

programs. There are many types of processors which include the

Intel Corporation's processors and the processors used in Apple computers.

MOTHERBOARD This is the main circuit board in the computer. It

provides expansion slots for peripherals, it holds the CPU and the memory.

They use buses to connect various components.

BIOS The BIOS (basic input output system) provides the processor

with the information required to boot the system from a non volatile storage unit.

It provides the system with the settings and resources that are available on the system.

It includes a test that helps verify the computer to meet requirements to boot up properly. This is called the Power On Self Test (POST).

POWER SUPPLY A power supply unit is the component that supplies power

to the other components in a computer. There are many types of power supplies the three main

ones would be, AT Power Supply ATX Power Supply ATX-2 Power Supply

FAN AND HEAT SINK The job of the heat sink is to keep the computer cool. There are two types of heat sink, Active heat sink

This utilises power and is usually a fan type. Passive heat sinks.

These are 100% reliable, as they have no mechanical components. They are made of an aluminium-finned radiator that removes heat through convection.

DISK CONTROLLERS The circuits that control data transfer to and from the disk

drive for example a floppy disk, hard disk or optical disc. Also from other ports such as USB and SATA.

In a PC, an IDE disk controller is typically built into the motherboard, and a cable plugs into the controller socket on one end and connects to the drive on the other.

PERIPHERALS A peripheral is a device attached to a host computer behind the

chipset whose primary functionality is dependent upon the host. Various types of common peripherals would be,

CAMERA You can use this to take photo graphs or images. You can then connect it

to the computer to view them or to print them off. PRINTER

This is an external hardware device. It is responsible for taking a hard copy of data. These are the most used peripherals.

PLOTTER This is similar to a printer. It used pen, pencil, marker or other writing tool

to make a design. These are commonly used for CAD and other print jobs.

SCANNER This allows you to take an image or text and convert it to a digital file.

You can connect this to a computer by USB, Parallel or SCSI port.

EXPANSION CARDS An expansion card is a printed circuit board that can

be inserted into an expansion slot of a computer motherboard to add additional functionality to a computer system.

A few common types of expansion cards such as network, graphic and Sam card can all be installed in a an available expansion slot.

BACKING STORAGE A backing storage is a computer storage device whose capacity is larger,

but whose access time is slower, than that of the computer's main storage or immediate access storage.

Flash memory This is ideal for many applications as it has high speed, stability and low

energy consumption. Some of the applications that use flash memory are digital cameras,

mobile phones and printers. Optical media

This stores binary data in a surface that reflects the light different depending on whether a 0 or 1 is stored.

Hard disks CD-R

These are blank but use a special read/write CD drive unit so that the user can store programs and data onto the disk. They can only be written on once.

CD-RW Users can read, write and delete files from the disks and much as they

want

INTERNAL TRANSMISSION Buses

This is a set of physical connections that can be shared by multiple hardware components meaning they can communicate with each other.

The purpose of these is to reduce the number of ‘pathways’ needed for communication between the components.

There are generally two buses within the computer, Internal bus (front-side bus or FSB)

This allows the processor to communicate with the system’s central memory.

Expansion This allows motherboard components to communicate with

one another. (USB, Serial and Parallel Ports, PCI connectors and hard drives)

Overclocking is an increase of speed size. To run a microprocessor faster than the speed for which it has been tested and approved.

EXTERNAL TRANSMISSION

MODEM This is a device that allows data over phone lines. The speed depends on the phone lines and the

technology used by your internet service provider.

PORTS USB

This is a serial bus to connect devices to the computer. Some of the pieces of hardware that can connect mice,

keyboards, PDAs and digital cameras to the computer. PARALLEL

This is commonly used to connect printers to the computer.

SERIAL This allows you to connect a serial device to the

computer. It is capable of transmitting one bit at a time. You can use a number of hardware components with the

serial port. These include the mouse, modem. Network and printer.

INTERNAL MEMORY Random Access Memory (RAM)

This is used to describe the memory within the computer. RAM requires power. When power is turned off then all the

data is lost Read-Only Memory (ROM)

This is capable of holding data and being read from. It is capable of keeping its contents whether there is

power or not