This is a list of a some hard to find publications on the Z80 CPU.
...continue reading "Z80 Library"
Month: September 2014
A Z80 : References
This design would not be possible without Ken Shirriff who reverse-engineered some major portions of Z80 from the picture of a die. These are the portions of the A-Z80 design that are based on his work:
A Z80 : The Soul
In the first post I described the sequencer, a circuit that provided discrete timing signals to space operations apart. In the second post I mentioned the Timing matrix that was run by these signals and orchestrated a dance of control signals in time.
This article is about making it all alive and kicking within an FPGA solution.
...continue reading "A Z80 : The Soul"
A Z80 : The Mind
In the last article I described the sequencer, which is the heart of a CPU, and a few other blocks that perform various tasks. But how is it all orchestrated to perform useful work?
Enter the PLA and theĀ Timing matrix - the mind of a CPU.
...continue reading "A Z80 : The Mind"
A Z80 : The Heart
Click on any image to open a higher-resolution version.
This is how it all works.
The sequencer is "the heart" of a CPU. It gets the external clock which in turn toggles two rows of flip-flops that generate machine cycles (M-cycles) and clock periods (T-states).
...continue reading "A Z80 : The Heart"
A Z80 From the Ground Up
A-Z80 is a conceptual implementation of the venerable Zilog Z80 processor targeted to synthesize and run on a modern FPGA device. It differs from the existing (mostly Verilog) Z80 implementations in that it is designed from the ground-up through the schematics and low-level gates.
...continue reading "A Z80 From the Ground Up"