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The functions of computer

a. Computer as data processing :

Data processing is the conversion of data into usable and desired form. This conversion or “processing” is carried out using a predefined sequence of operations either manually or automatically. Most of the data processing is done by using computers and thus done automatically. The output or “processed” data can be obtained in different forms like image, graph, table, vector file, audio, charts or any other desired format depending on the software or method of data processing used. When done itself it is referred to as automatic data processing.

Data Processing - Understanding Data

Fundamentals of data processing & how data is processed

Data processing is undertaken by any activity which requires a collection of data. This data collected needs to be stored, sorted, processed,analyzed and presented , This complete process can be divided into 6 simple primary stages which are:

  1. Data collection
  2. Storage of data
  3. Sorting of data
  4. Processing of data
  5. Data analysis
  6. Data presentation and conclusions

    Methods of data processing

    1. Manual data processing: In this method data is processed manually without the use of a machine, tool or electronic device.  Data is processed manually, and all the calculations and logical operations are performed manually on the data.
    2. Mechanical data processing – Data processing is done by use of a mechanical device or very simple electronic devices like calculator and typewriters. When the need for processing is simple, this method can be adopted.
    3. Electronic data processing – This is the modern technique to process data. Electronic data processing is the fastest and best available method with the highest reliability and accuracy. The technology used is latest as this method used computers and employed in most of the agencies. The use of software forms the part of this type of data processing. The data is processed through a computer; Data and set of instructions are given to the computer as input, and the computer automatically processes the data according to the given set of instructions. The computer is also known as electronic data processing machine.Sorting & Filtering of data

      Types of Data processing on the basis of process/steps performed

      1. Batch Processing
      2. Real-time processing
      3. Online Processing
      4. Multiprocessing
      5. Time-sharing

b. Computer as data storage :

Computers use a variety of data storage devices that are classified in two ways: one is whether they retain the data if there is no electricity and the other is how close they are to the processor (CPU). Both types of storage are needed in all computers. In a personal computer, memory does not retain data when the electricity is off, but while it is on, it enables quick access to open files. A storage drive, however, allows you to permanently store data, so it’s available each time you turn on the computer.

Volatile and non-volatile storage

The first classification of computer data storage is between volatile and non-volatile storage. An example of volatile storage is memory (RAM) that stores data only until there is no electricity powering the device. RAM allows your computer to have multiple files open and access any of them instantly. Some other examples of volatile storage devices are calculators.

A Crucial DDR4 UDIMM RAM memory module
Non-volatile storage is storage that maintains the data even when there is no electricity powering the device. An example is a hard disk drive (HDD) or solid state drive (SSD) that holds all of the data saved to your computer. There is other non-volatile storage, such as DVDs or flash drives.
Two examples of non-volatile storage including a USB flash drive and a Crucial SSD

Storage hierarchy

Computer data storage devices are also classified by their distance from the processor, or CPU. The closest storage is memory, or RAM. This is the only kind of data storage that directly accesses the CPU. Memory includes processor registers and the processor cache, but these are included on the memory module.

Memory is volatile storage, so any information that goes into memory needs to be written to the main storage device to be retained permanently. Because data flows from memory to a storage device, it’s considered secondary storage.

For most personal computers, secondary storage is the main data storage device. A hard disk drive or solid state drive holds all of the data; files, photos, programs, music, and movies, that the user wants to keep. Removable, external media storage devices such as flash drives and read/writeable CDs and DVDs are also secondary storage. A computer can’t function without a storage drive, however. The storage drive also holds all the information the computer needs to run.

Tertiary storage is computer data storage that uses removable media, such as a tape drive, and it uses a robot to retrieve the data. This is rarely used in personal applications.

c. Computer as data movement :

Data movement instructions move data from one place, called the source operand, to another place, called the destination operand. Data movement instructions can be grouped into loads, stores, moves, and immediate loads.

Load instructions move data from memory to registers.
Store instructions move data from registers to memory.
Move instructions move data from one register to another.
Immediate load instructions move constants, including addresses, to registers.

d. Computer as controlling system

A control system is a set of devices that work together to regulate an environment or achieve some set objectives.  This is achieved through a control loop.

Examples of control systems:

  • Maintaining healthy conditions in a fish tank
  • Automatic shop doors
  • Automatic street or security lighting
  • Burglar alarms
  • Automated greenhouses
  • Heating and cooling systems

How does a control system work?

To understand how a control system works, it helps to remember how a computer system is structured (see diagram below).

Computer System Diagram

  1. Input devices, usually sensors, send data readings to the microprocessor (computer) at set intervals
  2. To be understood, this data may have to be converted using an ADC (analogue to digital converter)
  3. The microprocessor compares the data readings against pre-set values that it has stored (using a control program)
  4. The microprocessor then makes a decision as to whether any action is needed (e.g. is more heat needed to maintain the pre-set value?)
  5. If needed, the microprocessor will send a signal to instruct an output device to do something (e.g. turn on heater, turn off oxygen pump etc)
  6. This may involve an actuator (e.g. a motor to open the gates or shop doors)
  7. This process repeats in a continuous loop


At no point does an input device directly communicate with an output device, or make any judgement calls.  Because of this, a statement such as the following is completely wrong:

“When it gets dark, the light sensor turns on the light bulb”

The computer system diagram above confirms this cannot happen.

Benefits of control systems

  • Computers are quick to respond to change and can process data very quickly
  • Can run all day every day, without wages or needing a break
  • Can operate in places dangerous to humans
  • Consistent and error free

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