Electrical Engineering

 Programmable Logic Array (PLA) A combinational circuit may occasionally have don’t care conditions. When implemented with a ROM, a don’t care condition become an address input that will never occur. The words at don’t care addresses need not to be programmed. Why PLA??   Consider for example, a combinational circuit that converts a 12-bit card code to a 6-bit internal alphanumeric code     Valid output = 47 If we use ROM size of ROM = 4096X6 The remaining 4096 words of ROM are not used and are thus wasted