This document provides an overview of Programmable Array Logic (PAL). It defines PAL as a commonly used programmable logic device with a programmable AND array and fixed OR array, making it easier to use but less flexible than a PLA. The document includes a block diagram of PAL, compares it to other programmable logic devices like PLA and ROM, provides an example of implementing Boolean functions with a PAL, and lists advantages such as being highly efficient, low cost, secure, reliable, and flexible.

1. Programmable
Array Logic
By Shaurya Bahl
(21CSU189)

2. Contents
• Definition of Programmable Array Logic
(PAL)
• Block Diagram of PAL
• Circuit Diagram of PAL
• Comparison with other Programmable
Logic Devices
• Example of PAL
• Advantages of PAL

3. Definition of
Programmable
Array Logic
(PAL)
• Programmable Array Logic (PAL) is a
commonly Used programmable logic device
(PLD). It has programmable AND array and
fixed OR array.
• It is easier to use but not flexible as
compared to Programmable Logic Array
(PLA) because only the AND array is
programmable.
• The Limitation of PAL is number of AND
gates.
• PAL consists of small Programmable Read
Only Memory (PROM) and additional
output logic used to implement a particular
desired logic function with limited
components.

4. Block Diagram of
Programmable
Array Logic

5. Circuit Diagram of
Programmable
Array Logic

6. Comparison
with other
Programmable
Logic Devices
• Main Difference between PLA, PAL and
ROM is their basic structure.
• In PLA, Programmable AND gate is followed
by programmable OR gate.
• In PAL, programmable AND gate is followed
by fixed OR gate.
• In ROM, fixed AND gate is followed by
programmable OR gate array.

7. Example of PAL (1 of 2)
• Example 1: Implement the Boolean functions
F1= A’BC’D + A’BCD’ + ABC’D and F2= A’BC’ +
A’BC + AB’C + ABC’ with PAL device.
• Solution: The given Boolean expressions can
be simplified to get a reduced equation:

8. Example of PAL (2 of 2)
• The simplified expression can be
realized using PAL. The given function
has four inputs and two outputs.
• It has five product terms. Each
Product term is obtained by placing
the fuse link to the corresponding
input line.

9. Advantages of PAL
• Highly Efficient
• Low Production cost as compared to PLA
• Highly secure
• High Reliability
• Low power required for working
• More flexible to design

10. Thank You