Key facts

  • This lesson focuses on the Senior Secondary CET computer topics of computer characteristics and applications, computer organization, memory, file syst...
  • A computer is an electronic data-processing machine: it accepts input, processes it under instructions, stores data, and produces output.
  • Common characteristics of computers are speed, accuracy, diligence, large storage, versatility, automation, and the absence of independent judgment.
  • Computer organization should be read as input unit, central processing unit, memory or storage, output unit, and the flow of data between them.
  • RAM is temporary working memory used while programs run; ROM keeps start-up instructions and retains data even when power is off.

Key Points at a Glance

  1. 1

    This lesson focuses on the Senior Secondary CET computer topics of computer characteristics and applications, computer organization, memory, file system, input-output devices, and MS Office.

  2. 2

    A computer is an electronic data-processing machine: it accepts input, processes it under instructions, stores data, and produces output.

  3. 3

    Common characteristics of computers are speed, accuracy, diligence, large storage, versatility, automation, and the absence of independent judgment.

  4. 4

    Computer organization should be read as input unit, central processing unit, memory or storage, output unit, and the flow of data between them.

  5. 5

    RAM is temporary working memory used while programs run; ROM keeps start-up instructions and retains data even when power is off.

  6. 6

    A file system organizes data into files and folders; extensions such as .docx, .xlsx, .pptx, .jpg, and .pdf indicate common file types.

  7. 7

    MS Word is for documents, MS Excel is for spreadsheets and calculations, and MS PowerPoint is for slide presentations.

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Computer characteristics

A computer is an electronic machine that works on data according to stored instructions. At the Senior Secondary CET level, do not define it only as a typing machine. Its basic cycle is input, processing, storage and output. For example, when marks are entered, the keyboard gives input, the processor calculates totals, memory and storage hold the data, and the screen or printer gives output.

The most important characteristics are speed, accuracy, diligence, storage capacity, versatility and automation. Speed means that a computer can complete a very large number of operations in a short time. Accuracy means that correct input and correct instructions usually give correct output. Diligence means it does not become tired or bored by repetitive work. Storage capacity allows large records to be kept and searched. Versatility means the same machine can prepare a letter, maintain an attendance sheet, show a presentation or process an online form. Automation means that after instructions are given, the computer can continue the defined task with little human intervention.

One limitation must be remembered: a computer does not have independent common sense. Wrong data or wrong instructions can still produce wrong output. This is why the phrase garbage in, garbage out is useful for exams.

Exam cue: characteristics questions usually ask why computers are useful in offices, schools, banks and public-service centres, and the answer is not only speed but speed plus accuracy, storage and repeatability.

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