2011/08/30

Data Representation

             Computers use the two-state system to represent data. Such a two state system is referred to as a binary system. In computers these two states are denoted by the digits 0 and 1 and any such value is called a binary digit or bit. In side the computer these two states are typically implemented by using two different voltages.

             The smallest unit of data that can be stored in a computer is a bit. A bit will have the value '0' or '1' . A large collection of such '0's or '1's is what makes up data in a computer.

Smallest Unit           = 1 bit
8 bits                     = 1 byte (B)
1024 bytes             = 1 kilobyte (KB)
1024 kilobytes        = 1 megabyte (MB)
1024 megabyte       = 1 gigabyte (GB)
1024 gigabyte         = 1 terabyte (TB)
(In computer jargon, One Kilo = 1024)

              The capacity of a particular storage device and the space taken up by a file are always measured using these units.

              Letters, numbers and special characters are represented within a computer by means of a binary coded scheme. Three popular binary coding schemes use eight bits to represent characters whereas Unicode uses 16 bits.



Character
ASCII-8
EBCDIC
Character
ASCII-8
EBCDIC

A
B
C
D
E
F
G
H
I
J
K
L
M


0100 0001
0100 0010
0100 0011
0100 0100
0100 0101
0100 0110
0100 0111
0100 1000
0100 1001
0100 1010
0100 1011
0100 1100
0100 1101


1100 0001
1100 0010
1100 0011
1100 0100
1100 0101
1100 0110
1100 0111
1100 1000
1100 1001
1101 0001
1101 0010
1101 0011
1101 0100


N
O
P
Q
R
S
T
U
V
W
X
Y
Z

0100 1110
0100 1111
0101 0000
0101 0001
0101 0010
0101 0011
0101 0100
0101 0101
0101 0110
0101 0111
0101 1000
0101 1001
0101 1010


1101 0101
1101 0110
1101 0111
1101 1000
1101 1001
1110 0010
1110 0011
1110 0100
1110 0101
1110 0110
1110 0111
1110 1000
1110 1001


0
1
2
3
4
!

0011 0000
0011 0001
0011 0010
0011 0011
0011 0100
0010 0001

1111 0000
1111 0001
1111 0010
1111 0011
1111 0100
0101 1010


5
6
7
8
9
;

0011 0101
0011 0110
0011 0111
0011 1000
0011 1001
0011 1011


1111 0101
1111 0110
1111 0111
1111 1000
1111 1001
0101 1110



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