Parts of computers

•Four parts:

•Input device

•Processor (small silicon chip, microprocessor, video recorder, dedicated)

•Output device

•Storage Device

Input

Storage

Processing Output

Communications

Input Devices• Keyboards (qwerty, 100 years, piano keyboard, ATM)• Pointing devices (touch sensitive screens) mouse, tracker ball,

touch pad, joystick.• Video digitisers and scanners (analogue to digital converter, small

squares named pixels)• Remote control (buttons send coded signal to the device)• Magnetic input devices (magnetic stripes and magnetic ink,

MICR).• Optical mark readers (OMRs, detect marks made in pencil)• Graphics tablets (young or disabled children)• Light pens (on screen send computer, filling forms.)• Microphones (input sounds to a computer file, analogue to dig.)• MIDI (between the computer and the instrument, interface)• Sensors ( input data from the physical world)

– Temperature, sound, magnetism, radar, light, pressure, touch, microwave).

Output DevicesTwo categories:

• Designed to be understood by humans

• Automatic

Monitors/ screens: tiny squares called pixels

Quantity of pixels = Resolution

Refreshing

Colour – monochrome

Input when it is a touch screen

Printers: Produce hard copy

Colour – Black and white

Dots – image

types: laser printer

inkjet printer

dot matrix printer

Output Devices• Laser – positive charge spray ink

– Quality– Quickly– Expensive

• Inkjet - squinting ink at the piece of paper.Bit a bit.– Quality– Slow– Cheap

• Dot matrix – Pins that hit an ink ribbon– Poor quality– Slow– Use with carbon copies.– Cheap

Plotter: Pens moved around on a sheet of paper. Architectural drawings

http://es.wikipedia.org/wiki/Imagen:Plotter_Gerber_Infinity.jpg

Output Devices

• Speakers: used to produce sound.• Control devices: automating process control. Fan.

Selecting input and output devices

– Where will the devices be used?– What will they be inputting or outputting?– Who is going to use it?