This document discusses two early digital codes: Baudot code and ASCII code. [1] Baudot code used 5 bits to represent 32 characters and was used in telegraph systems in the late 1800s. [2] ASCII code uses 7 bits to represent 128 characters and became widely used for data representation and transmission within computer networks. [3] Both codes allowed data to be represented digitally to facilitate transmission and processing, though ASCII provided more possible characters and became the more common standard.

1. In The Name Of ALLAH,The Most Beneficent
and Merciful.
Shahzada Saleem 1421-310026
Muhammad Usman 1421-310060
Data Communications

2. The way in which data is represented.
The sender and receiver use same code.
Here we discuss two types of codes….

4. Jean-Maurice-Emile Baudot
French telegraphengineer and inventor of the first
means of digital communication Baudot code
Baudot's hardware had three main parts: the
keyboard, the distributor, and a paper tape.
Five bits allowed 32 different characters .

5. Baudot
keyboard,
telegraph
1884

6. Values Ltrs Shift FIGS Shift Values Ltrs Shift FIGS Shift
3 A - 23 Q 1
25 B ? 10 R 4
14 C : 5 S
9 D Who are you? 16 T 5
1 E 3 7 U 7
13 F ! 30 V ;
26 G & 19 W 2
20 H # 29 X /
6 I 8 21 Y 6
11 J Bell 17 Z “
15 K ( 0 BLANK BLANK
18 L ) 31 LTRS LTRS
28 M . 27 FIGS FIGS
12 N , 4 SPACE SPACE
24 O 9 8 CR CR

7. Symbols are all of equal size and therefore
decoding them using a table would be easier
Baudot code is resilient in the presence of
transmission errors

8. Limitation on the number of characters it can
represent - total of 62 characters
Apparent lack of logic in the way the characters
and the numbers have been allocated - the bit pattern
for the number one (11101) is numerically larger than
the bit pattern for the number nine (00011).

9. ASCII stands for American Standard Code for
Information Interchange.
ASCII code is the numerical representation of a
character
It is seven bits 128 combinations.

12. As data is represented by seven bits 128
different combinations are possible
Usually transmitted as 8-bits and thus one
bit can be employed for simple error detection
ASCII code is widely used for representation
in the internal structure of a computer and
thus translation is not normally required if
information is to be transmitted over a network

13. Occasionally much of the information to
be transmitted will be relatively similar
and thus the seven-bit code can waste
space