Programmable Logic Devices: PAL, GAL, CPLD

This lecture introduces the concepts of Programmable Array Logic (PAL), Generic Array Logic (GAL), and Complex Programmable Logic Devices (CPLD). PAL technology allows the realization of any logic function with fixed input-to-output delay and low power consumption. GAL technology overcomes the limitations of PAL by using distributed routing and pass-gates. CPLDs, with their macro-cells and routing arrays, handle the increasing complexity of digital systems. The lecture also covers the transition from CPLDs to Field Programmable Gate Arrays (FPGAs), highlighting the use of Look Up Tables (LUTs) and distributed routing in FPGAs. It explains the architecture, place and route process, and the evolution of FPGAs from CPLDs, emphasizing the importance of Hardware Description Languages (HDLs) like VHDL and Verilog for FPGA design.