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.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.