Computer Knowledge: Computer Codes and Data Representation in Computers for Bank and Other Competitive Exams

Data Representation in Computers & Computer Codes

As we know that computer understand the binary language (o's and 1's) for the data representation. All kinds of data, i.e., alphabets, numbers, symbols, sound data or video are represented in terms of 0's and 1's. There are two basic types of data, which are stored and proceed by computers, namely characters and numbers. The characters include letters and special symbols while numbers include digits from 0 to 9.

Number System: A number system defines a set of values that is used to represent quantity. Digital computers internally use the binary number system to represent data and perform arithmetic calculations.

Types of Number System:

The number systems generally used by a computer are as follows

1. Binary Number System: The binary system is very efficient for computers, but not for humans. It contains two unique digits 0's and 1's. It is also known as Base 2 system. The binary numbers 0 and 1 called a bit. The computer always calculates input in binary form. Ex:- 1010101

2. Decimal Number System: It consists of ten digits from 0 to 9. These digits can be used to represent any numeric value. It is also known as Base 10 system or positional number system.

3. Octal Number System: It consists of 8 digits from 0 to 7. It is also known as Base 8 system. Each position of the octal number represents a successive power of eight.

4. Hexadecimal Number System: It provides us with a shorthand method of working with binary numbers. There are 16 unique digits available in this system. These are 0 to 9 and A to F, where A denotes 10, B denotes 11.............F denotes 15. It is also known as Base 16 system or simply Hex. So, each position of the hexadecimal number represents a successive power of 16.

Computer Codes

In computer, any characters like alphabet, digit or any special character is represented by collection of 1 and 0 in a unique coded pattern. In computers, the code is made up of fixed size groups of binary positions.

1. Binary Coded Decimal (BCD):

Binary coded decimal is a number system where four bits are used to represent each decimal digits. BCD is a method of using binary digits to represent the decimal digits (0-9). In Binary Coded Decimal system, there is no limit on size of a number. This system was developed by IBM corporation.

2. American Standard Code for Information Interchange (ASCII):

ASCII characters are represented by seven bits. There are standard character codes used to store data so that it may be used by other software programs. The standards ASCII codes defines 128 character codes (from 0 to 127). Basically, ASCII codes are of two types-ASCII-7 and ASCII-8.

ASCII-7, is a 7-bit standards ASCII code. It allows 2⁷ = 128 unique symbols.

ASCII-8, is a extended version of ASCII-7, it is an 8-bit code, allows 2⁸ = 256 unique symbols or characters.

3. Extended Binary Coded Decimal Interchange Code (EBCDIC):

In EBCDIC, characters are represented by eight bits. These codes store information which is readable by other computers. It allows 2⁸ = 256 combinations of bits.