Coding systems, also known as character encoding or character sets-(BCD),(EBCDIC),(ASCII),Unicode

Coding systems

Coding systems, also known as character encoding or character sets, are used to represent text and other characters in a digital format. There are several coding systems in use today, each with its own history and purpose. In this blog post, we will discuss four major coding systems: Binary Coded Decimal (BCD), Extended Binary Coded Decimal Interchange Code (EBCDIC), American Standard Code for Information Interchange (ASCII), and Unicode. We will also provide a BCD table to illustrate how BCD is used to represent numbers in a digital format.

Binary Coded Decimal (BCD)

Binary Coded Decimal (BCD) is a coding system that represents numbers using a four-bit binary code for each decimal digit. In BCD, each decimal digit is converted into a binary code between 0000 and 1001. For example, the number 123 would be represented as 0001 0010 0011 in BCD.

BCD is mainly used in electronic devices, such as calculators and digital clocks, where accurate decimal arithmetic is required. It is also used in banking systems and financial applications where accuracy is crucial.

Here is a table to show how BCD represents numbers:

Decimal	BCD
0	0000
1	0001
2	0010
3	0011
4	0100
5	0101
6	0110
7	0111
8	1000
9	1001

Extended Binary Coded Decimal Interchange Code (EBCDIC)

The Extended Binary Coded Decimal Interchange Code (EBCDIC) is a coding system that was developed by IBM for use in mainframe computers. EBCDIC uses an eight-bit binary code to represent each character, allowing for up to 256 characters to be represented.

EBCDIC is mainly used in mainframe computers and legacy systems, where it is still in use today. However, it has largely been replaced by ASCII and Unicode in modern computing.

Here is a table to show how EBCDIC represents characters:

Character	EBCDIC Code
A	1100 0001
B	1100 0010
C	1100 0011
D	1100 0100
E	1100 0101
F	1100 0110
G	1100 0111
H	1100 1000
I	1100 1001
J	1100 1010

American Standard Code for Information Interchange (ASCII)

The American Standard Code for Information Interchange (ASCII) is a coding system that was developed in the 1960s by the American National Standards Institute (ANSI). ASCII uses a seven-bit binary code to represent each character, allowing for up to 128 characters to be represented.

ASCII is widely used in modern computing and is supported by most operating systems and programming languages. It includes a range of characters such as letters, numbers, and punctuation.

Here is a table to show how ASCII represents characters:

Dec  Char                           Dec  Char     Dec  Char     Dec  Char
---------                           ---------     ---------     ----------
  0  NUL (null)                      32  SPACE     64  @         96  `
  1  SOH (start of heading)          33  !         65  A         97  a
  2  STX (start of text)             34  "         66  B         98  b
  3  ETX (end of text)               35  #         67  C         99  c
  4  EOT (end of transmission)       36  $         68  D        100  d
  5  ENQ (enquiry)                   37  %         69  E        101  e
  6  ACK (acknowledge)               38  &         70  F        102  f
  7  BEL (bell)                      39  '         71  G        103  g
  8  BS  (backspace)                 40  (         72  H        104  h
  9  TAB (horizontal tab)            41  )         73  I        105  i
 10  LF  (NL line feed, new line)    42  *         74  J        106  j
 11  VT  (vertical tab)              43  +         75  K        107  k
 12  FF  (NP form feed, new page)    44  ,         76  L        108  l
 13  CR  (carriage return)           45  -         77  M        109  m
 14  SO  (shift out)                 46  .         78  N        110  n
 15  SI  (shift in)                  47  /         79  O        111  o
 16  DLE (data link escape)          48  0         80  P        112  p
 17  DC1 (device control 1)          49  1         81  Q        113  q
 18  DC2 (device control 2)          50  2         82  R        114  r
 19  DC3 (device control 3)          51  3         83  S        115  s
 20  DC4 (device control 4)          52  4         84  T        116  t
 21  NAK (negative acknowledge)      53  5         85  U        117  u
 22  SYN (synchronous idle)          54  6         86  V        118  v
 23  ETB (end of trans. block)       55  7         87  W        119  w
 24  CAN (cancel)                    56  8         88  X        120  x
 25  EM  (end of medium)             57  9         89  Y        121  y
 26  SUB (substitute)                58  :         90  Z        122  z
 27  ESC (escape)                    59  ;         91  [        123  {
 28  FS  (file separator)            60  <         92  \        124  |
 29  GS  (group separator)           61  =         93  ]        125  }
 30  RS  (record separator)          62  >         94  ^        126  ~
 31  US  (unit separator)            63  ?         95  _        127  DEL

Unicode

Unicode is a coding system that was developed in the 1990s to address the limitations of ASCII and other coding systems. Unicode uses a variable-length encoding scheme that can represent over 1 million characters from different scripts and languages.

Unicode is widely used in modern computing and is supported by most operating systems and programming languages. It includes a vast range of characters such as letters, numbers, symbols, and emojis.

Here is a table to show how Unicode represents characters:

Character Unicode Code

Character	Unicode Code
A	U+0041
B	U+0042
C	U+0043
D	U+0044
E	U+0045
F	U+0046
G	U+0047
H	U+0048
I	U+0049
J	U+004A

Conclusion

Coding systems are crucial for representing text and other characters in a digital format. Each coding system has its own strengths and limitations, and choosing the right one depends on the specific application. In this blog post, we discussed four major coding systems: Binary Coded Decimal (BCD), Extended Binary Coded Decimal Interchange Code (EBCDIC), American Standard Code for Information Interchange (ASCII), and Unicode. We also provided a BCD table to illustrate how BCD is used to represent numbers in a digital format.