TABLE OF CONTENTS In Chapter 5, we discussed various combinational circuits that are commercially available in IC packages. We also saw how other combinational circuits and Boolean functions are realized with the help of these commercially available IC packages. With the advent of large-scale integration technology, it has become feasible to fabricate large circuits within a single chip. One such consequence of this technology is the Programmable Logic Devices or PLDs.
The advantages of using programmable logic devices are:
Reduced space requirements.
Reduced power requirements.
Design security.
Compact circuitary.
Short design cycle.
Low development cost.
Higher switching speed.
Low production cost for large-quantity production.
In earlier chapters, we have seen that any Boolean function or combinational circuit can be represented by sum of the products form or sum of the required minterms. It was also shown that a decoder generates 2 n minterms for n number of input variables and required minterm outputs of a decoder are fed to an OR gate to obtain a desired function. This fact leads to the development of IC packages with larger integration that contain decoders with a number of OR gates or one single chip containing a large number of basic gates AND, OR, and NOT. These ICs are programmed according to desired functions by the manufacturers or the designers. Another advantage of employing these ICs is that one single IC can generate multiple outputs, thus reducing the board space,...
