Page 10 - DCAP206_INTRODUCTION_TO_COMPUTER_ORGANIZATION_AND_ARCHITECTURE_DCAP502_COMPUTER_ORGANIZATION_AND_ARCHITECTURE

Unit 1: Review of Basics of Digital Electronics

Notes
Example: Codes 2421 and excess-3 are reflective. In code 2421: we know that the positional
weights are 2, 4, 2 and 1. The following figure shows an example of reflective code where the
complement of 8 is 1 and the complement of 7 is 2.

4. Sequential Codes: Sequential codes are codes in which the succeeding code is one binary
number greater than its preceding code. This assists in mathematical data manipulation.

Example: 8421 and excess-3 codes are sequential codes.
5. Cyclic Codes: In cyclic codes, only one bit in the code changes at a time while moving from one
number to the next. It is a non-weighted code, which means that the position of bit does not
contain any weight.
Table1.1 shows the bit patterns assigned for gray code from decimal 0 to 10.

Table 1.1: Decimal Code to Gray Code Conversion

Decimal code Gray code

0 0000
1 0001
2 0011
3 0010
4 0110
5 0111
6 0101
7 0100
8 1100
9 1101
10 1111

6. Error Detecting Codes: Whenever data is transmitted from one point to another, there is a
probability that the data may get corrupted. In order to detect these data errors, some special
codes called error detection codes are used.

LOVELY PROFESSIONAL UNIVERSITY 3