Parts of computers Four parts: Input device Processor (small silicon chip, microprocessor, video recorder, dedicated) Output device Storage Device

Input Storage ProcessingOutput 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 Devices Two 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

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?