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Data bus on the Z80 processor is 8 bits wide. Data bus wires carrying information within the chip itself do not simply connect to package pins and out to the world - the gate circuitry of each bit is quite complex. This article presents a transistor level schematic of a data bit’s gate which I reverse-engineered from a die photograph.
...continue reading "The Anatomy of a Z80 Gate"


After reading excellent Ken Shirriff's blog on reverse-engineering parts of the Z80 CPU, I decided to learn how to decipher some of the chip die-shots myself. It turns out not to be that difficult if you follow certain guidance which I will describe in this post.
...continue reading "Z80 Instruction Register deciphered"