5.3 Combinational PLDsProgrammableLogicArraysHistorically, the first PLDs were programmablelogic arrays (PLAs).A PLA is a combinational, two-level AND-ORdevice that can be programmed to realize anysum-of products logic expression, subject to thesize limitations of the device.Limitations are> The number of inputs (n)> The number of outputs (m)> The number of product terms (p)NextReturn
Limitations are Ø The number of inputs (n) Ø The number of outputs (m) Ø The number of product terms (p) 5.3 Combinational PLDs Return Next n Programmable Logic Arrays Historically, the first PLDs were programmable logic arrays (PLAs). A PLA is a combinational, two-level AND-OR device that can be programmed to realize any sum-of products logic expression, subject to the size limitations of the device
2314P1P2P5P4P3P601kk0203XA 4x3 PLA with six product terms
I1 I2 I3 I4 O1 O2 O3 P1 P2 P3 P4 P5 P6 A 43 PLA with six product terms
11123-14P6P1P2P4P5P3010203Compact representation of a 4x3 PLAwith six product terms
I1 I2 I3 I4 O1 Compact representation of a 43 PLA with six product terms O2 O3 P1 P2 P3 P4 P5 P6
1213T14P4P1P2P3P5P6010203
I1I2I3I4 O1 P1 P2 P3 P4 P5 P6 O2O3
5.3 Combinational PLDsProgrammableArrayLogicDevicePAL16L8(P341)0111101.BackNextReturn
5.3 Combinational PLDs Return Back Next n Programmable Array Logic Device I2 I1 I3 O1 IO1 PAL16L8 (P341)