Z80 Explorer is a Zilog Z80 netlist-level simulator capable of running Z80 machine code and also an educational tool with features that help reverse engineer and understand this chip better.Continue reading
The 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.
Data pins (D0-D7) carry arguably the most complex signals on the Z80 since they are both bi-directional and capable of tri-stating. They are located around the +5V pin – four of them on each side. This is a microphotograph of a gate of one of the data pins which we will look at more closely today – a pin for a data line D6.