Computer hardware

Published on 12/06/2015 by admin

Last modified 22/04/2025

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2 Computer Hardware

Computer	A device for processing information quickly and easily, and comes in many shapes and sizes
Computer Types	Mainframe A large computer, usually the centre of a system. Intelligent peripherals can then be attached to this.
Computer Types	Personal computer (PC) A general purpose machine that enables the user to perform a number of tasks including using word processing, spreadsheets, databases, e-mail, internet access • Desktop computers used in a permanent position usually have a: Tower that holds the computer A monitor A separate keyboard A mouse • Laptop small computer usually contains everything in one box: Computer, monitor and touch screen • Personal Digital Assistant (e.g. a ‘Blackberry’) A small, handheld, wireless computer which performs all the tasks of a personal computer
Main Parts	Central Processing Unit (CPU) The microprocessor that controls the working of the computer in the three main areas of: • The memory Area used to hold data • The arithmetic logic Performs mathematical calculations, including logic functions • Control unit Fetches information Stores the information Interprets the information
	Hard disk Permanent store for: • Programs • Files • Documents, etc.
	Operating system Integral software • Allows the operator to communicate with the computer
	Power supply Electricity is supplied via a step-down transformer
Types of Memory	Random Access Memory (RAM) Temporarily stores the information the computer is working with • Where a program is loaded when it is being used • The higher the RAM the faster the computer will work
	Read Only Memory (ROM) A permanent memory store • It cannot be changed and remains when the computer is switched off • Used for basic information that does not change
	Basic input/output system Used when the computer is switched on • Establishes the basic connections
	Virtual memory A temporary data store on the hard drive • Interacts with RAM when required
Circuit Boards	Motherboard Main circuit board of a computer • Holds the CPU and the Memory
	Sound card Used to record and play audio • Converts analogue sound to digital information • And digital information to analogue
	Graphics card Used to display images on the monitor
	Network card Used to enable one computer to directly connect with another via a network connection
Interfaces	Integrated Drive Electronics (IDE) The main interface between: • The hard drive and the disk drive
	Peripheral Component Interconnect (PCI) Slots into the motherboard • A common method of connecting additional components, e.g. additional memory cards
	Small Computer System Interface (SCSI) Means of adding additional devices, e.g. scanners
	Accelerated Graphics Port (AGP) A high speed connection • Enables the graphics card to interface with the computer
Connections	Input/outputs The interaction between the computer and the components • Monitor – displays information (see Monitor Technology p. 21) • Keyboard – main method for entering information • Removable storage – DVDs, etc. (see Image Storage p. 45)
	Ports ‘Sockets’ • Parallel – usually used to connect a printer • Serial – usually used to connect an external modem • Universal Serial Bus (USB) – most common external connection used to connect: A mouse, printers, etc.
	Networks External communications enabling multiway communication • Local Area Network (LAN) a method of connecting computers in the same area (see Computer Networking p. 53) • Intranet a network of computers within a specific area, e.g. a hospital or group of hospitals • PACS Picture Archiving and Communications System, for allowing transfer of images and data across the intranet, e.g. radiographs and reports • Healthlink a centralised, data communications network, which enables authorised users to exchange documents and information
	Modem (MOdulator-DEModulator). A device, or interface, also known as an acoustic coupler • Means of connecting a computer to the internet
Accessories	Mouse Equipment to navigate round a computer monitor and to interact with it • It makes the computer more ‘user friendly’ • It is used by rolling the device across a desk top which, moves a cursor to icon displays on the screen
	Touch screen A type of mouse found on laptop computers • Controlled by finger tip pressure on the screen
	Printers • Inkjet printer Ink is sprayed on to paper through very fine jets Characters or images are built in very fine dots virtually silently Typically resolutions of 300 × 300 d.p.i. (dots per inch) can be expected Some ink cartridges contain the printhead • Laser printer Does not use ink cartridges but ‘toner’ The characters or images are built up by being scanned by a laser and then toner is fused onto the paper Resolution (up to 600 × 600 d.p.i.)
	Scanner A device which enables documents, pictures, etc. to be scanned • The resultant scan is held as a digital image
Communicating with a Computer	Light pen A device, shaped like a pen, which interfaces with a computer screen to enable writing, drawing or to click menu buttons. Enables signatures to be recorded on computer documents
	Speech recognition Software, allowing computers to be operated by human voice commands
	Speech synthesis Software allowing the computer to ‘talk’ to the user
	Barcode reader A barcode is a series of black and white parallel lines of varying thickness, each line representing a number. These can be scanned by either: • Using a light beam The reflected beam is detected by a charge-coupled device The analogue signal is converted to a digital signal • Or a laser beam Works as the light beam Can be used at a larger distance Is more expensive The information is then decoded by the computer and therefore in the hospital situation, patient identification information can be produced as a bar code and when scanned automatically added to the appropriate field on the screen