2.2. Part of a computer system

 

User

Data and information

Data is a collection of unprocessed items, which can include text numbers, images audio and video.

Data is raw facts and figures by its self it doesn't provide anything meaningful.

Information: Is processed data. It has meaning and is useful to one or more people.

 

Information processing cycle

A computer processes input (data) into output (information). Most people refer to the series of input, process, output and storage activities as the information processing cycle.

Ø  Input: this is the first stage in the cycle. This stage involves collection of data from the outside or also from within the system. The commonly used input devices are keyboard, bar code readers, mouse, scanners e.t.c 

Ø  Processing: This is the stage where by the computer works on the data entered and makes it usable.

Ø  Output: this is the stage in which the processed information is now transmitted to the user. The output can be given inform of audio, video, text and graphics. Results can be viewed on the screen or printed on a physical medium.

Ø  Storage: after the data has been processed into information the results can be kept for future use.

How a computer represents data

The computer reads and stores data of all kinds in form of numbers.

Computers use the binary number system while humans normally use decimal number system. 

Binary number system

Ø  Has two distinct digits, 0 and 1

Ø  0 and 1 combine to make numbers.

Decimal number system

Ø  Contains ten distinct digits e.g 0 up to 9.

Ø  Digits combine to make larger numbers.

Digital data representation

The form in which information is conceived manipulated and recorded.

Bit (binary digit)

Ø  It is the smallest possible unit of data a computer can recognize or use.

Ø  In other words, it is the smallest unit of data representation.

0 (off, No) OR 1 (on, Yes).

Byte

Ø  The Smallest unit of data Storage.

Ø  A byte is 8 bits, about one character of data.

Ø  Half a byte is a nibble.

Bits and bytes

Ø  One bit is a single 0 or 1.

Ø  One byte consists of 8 bits.

Ø  One kilobyte consists of 1,024 bytes approximately 1000 bytes.

Ø  One megabyte is 1,024 kilobytes or approximately 1 million bytes.

Ø  One gigabyte is 1,024 megabytes or approximately 1 billion bytes One terabyte is 1,024 gigabytes or approximately 1 trillion bytes.