Digital Systems

Chapter 11

Code Converters, Comparators and Other Logic Processing Circuits

OBJECTIVE

In Chapter 9, we learnt that AND-OR arrays, OR-AND arrays, NANDs and NORs are the building blocks of combinational logic circuits. In Chapter 10, we learnt that full adder circuits, decoders, encoders and multiplexers can also be used as the bigger building blocks for the logic design.

We will learn some important logic processing circuits, namely, code converters, digital comparator for magnitude and equality, parity generators and checkers, and bit-wise AND, OR, NOT logic processing circuits.

11.1 CODE CONVERTERS

11.1.1 Codes for Decimal Numbers

11.1.1.1 Common BCD Code

Recall the Equation (2.6) of Chapter 2.

A general formula to get the total N is again ...