Computer hardware

Published on 12/06/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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2 Computer Hardware

Types of 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.
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:

image Tower that holds the computer
image A monitor
image A separate keyboard
image A mouse

• Laptop small computer usually contains everything in one box:

image 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

image Area used to hold data

• The arithmetic logic

image Performs mathematical calculations, including logic functions

• Control unit

image Fetches information
image Stores the information
image 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:

image 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

image Ink is sprayed on to paper through very fine jets
image Characters or images are built in very fine dots virtually silently
image Typically resolutions of 300 × 300 d.p.i. (dots per inch) can be expected
image Some ink cartridges contain the printhead

• Laser printer

image Does not use ink cartridges but ‘toner’
image The characters or images are built up by being scanned by a laser and then toner is fused onto the paper
image 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

image The reflected beam is detected by a charge-coupled device
image The analogue signal is converted to a digital signal

• Or a laser beam

image Works as the light beam
image Can be used at a larger distance
image 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

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