Development of Computers

Development of Computers The earliest known device to record computations was the abacus. It dates back to ancient times and was invented by the Chinese. Ten beads were strung onto wires attached to a frame. Addition and subtraction were read from the final positions of the beads. It was considered the first manual tool used in calculating answers to problems that provided information and in a primitive way storing the results. Abacus Mechanical Clock During the Middle Ages the first closed system in terms of calculating information was invented by use of a mechanical clock. The parts of the clock calculated the time of day. The time was displayed through the position of two hands on its face. The inventor pre-programmed the clock instructions through the manner in which the pull of the weights and the swing of the pendulum with the movement of the gears established the position of the hands on the clock face. Mathematics John Napier (Scotsman mid 1600s) discovered logarith

Scanning Devices

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3. Scanning Devices

  • -These are devices that capture data directly into the computer.
  • -They can also be defined as devices that use a magnetic or photo-electric source to scan and convert images into electric signals that can be processed by an electronic apparatus, such as a computer.

Uses of Scanning Devices

Scanning devices are commonly used to:

  • -Convert a text document into an electronic file;
  • -Convert a photograph into an electronic graphic file;
  • -Sense an image to be sent over a voice frequency
  • -Circuit, such as a fax machine;
  • -Reproduce text and images, as with a copier.

 Classification of scanning devices

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Scanners are classified according to technology used to capture data namely: optical and magnetic scanners.

 Optical scanners

These scanners capture data using optical or light technology.
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Examples of optical scanners

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Bar Code and Scanner types

Magnetic scanners

 These scanners use magnetic technology to capture handwritten and magnetic strip data. E.g. MICR (magnetic ink character recognition), card readers etc 

MICR-Magnetic Ink Character Recognition

these scanners are used to read characters written using magnetic ink as shown left. Mostly used in banks to read cheques

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Magnetic Ink Character Recognition (MICR)
kcse computer studies
Inked Characters

Card Readers

 A magnetic card reader is a device which reads information contained in a encrypted sequence on a magnetic strip
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Card Reader


Also known as graphic tablet, allows a user to draw an image using a stylus
computer notes kcse form 1
Digitizer and a Stylus

 Digital camera

Also known as a digicam. Is a camera that takes video or still photographs by recording images on an electronic image sensor

form 1 computer notes
Digital Camera


Touch screen

It is an electronic visual display that can detect the presence and location of a touch within the display area.
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Touch Screen

 Voice input

Also known as speech recognition (SR). Is the translation of spoken words into text.
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Voice Input

Interactive Whiteboard (IWB) 

It is a large interactive display that connects to a computer and projector. A projector projects the computer's desktop onto the board's surface where users control the computer using a pen, finger, stylus, or other device. The board is typically mounted to a wall or floor stand.

they are used in a variety of settings, including classrooms at all levels of education, in corporate board rooms and work groups, in training rooms for professional sports coaching, in broadcasting studios and others.
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