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

Computer systems

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 Computer systems

kcse computer notes
computer system

  • A system- a system is a collection of entities that work together of achieve a common goal
  • A computer system-is a collection of entities (hardware, software, liveware, and firmware) that work together to receive process, manage and present information in a meaningful format.
  • Liveware- can also be termed as wetware and greyware. This word is used to describe a computer user.
  • Hardware- this is the tangible parts of a computer i.e. keyboard, mouse, CPU, monitor etc
  •  Software- can be described as computer programs or this is the intangible parts of a computer i.e. computer programs etc
  • Firmware- these are manufacturer’s settings though, can be classified under software i.e. programs in ROM chips 


KCSE computer revision notes and tutorials
Computer hardware Classification
  • Input devices- these are devices that convert input data from human readable form into machine readable form. or you can simply say, these are devices that enter data into the computer. Data can be classified as text data which consist of letters, numbers and symbols, graphic data which consist of diagrams, pictures, videos, clip arts, icons etc., voice data that consist of sound clips, input commands which are instructions entered mostly by pointing devices
  1. Human readable form is a kind of language that the user understands i.e. Kiswahili, English etc
  2. Machine readable form this is a language that the computer understands i.e. binary language, assembly language etc 

    Keying devices

    these are devices that converts typed numbers, letters and special characters into machine readable form examples: keyboard and keypad. These devices usually enter text data and command input into the computer examples:
    • Keyboard- this is the most commonly used keying method with desktop and laptop computers. such as:traditional keyboard, flexible keyboard, ergonomic, wireless etc
    • Keypad- this is a small keyboard used with hand held devices i.e. cell phones, calculators, notebooks etc

    Keyboard Classification

kcse computer studies notes
Classification of the keyboard


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