The 8085 processor uses a PLA (programmable logic array) to control much of the activity within the processor, such as instruction decoding and controlling the data flow between components of the chip. Pavel Zima has reverse-engineered the transistor-level circuitry of the 8085 microprocessor. I’ve looked into this in a bit more to figure out the architecture of the Programmable Logic Array, which takes up a large fraction of the chip. The PLA circuit is much more complex than the PLA on the 6502, for instance. It turns out that Pavel is ahead of me with information on the decode and timing PLAs, but the information below may still be of interest.
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