PAL
PAL stands for Programmable Array Logic and is a widely used PLD (Programmable Logic Device). It consists of a programmable AND and fixed OR array. It consists of a small PROM (programmable read-only memory).
For example:
Let us assume a given function using PAL.
There are three inputs, A, B, C, and three functions, X, Y, Z.
Using SOP terms, the function is expressed as follows:
X(A,B,C)=Σ (2,3,5,7)
Y(A,B,C)=Σ (0,1,5)
Z(A,B,C)=Σ (0,2,3,5)
It can also be understood through the following truth table:
| A | B | C | X | Y | Z |
| 0 | 0 | 0 | 0 | 1 | 1 |
| 0 | 0 | 1 | 0 | 1 | 0 |
| 0 | 1 | 0 | 1 | 0 | 1 |
| 0 | 1 | 1 | 1 | 0 | 1 |
| 1 | 0 | 0 | 0 | 0 | 0 |
| 1 | 0 | 1 | 1 | 1 | 1 |
| 1 | 1 | 0 | 0 | 0 | 0 |
| 1 | 1 | 1 | 1 | 0 | 0 |
The output for each function will be:
X=A’B+AC
Y=A’B+B’C
Z=A’B+A’C+AB’C
Advantages:
- It is highly efficient.
- It has a lower production cost.
- It is highly secure.
- It is highly reliable.
- It needs lower power.
- It is more flexible to design.
Reference