Arduino and Z80, how I did my design.

Hi everyone,

I would like to share how I built a small Z80 micro with the help of a Arduino.
Photo of the beauty:

The adressbus on the Z80 is wired to the arduino using two linked shiftregisters.
The databus is wired directly with one shiftregister.
One 32k sram is wired directly to the Arduino and also to the Z80.
On the Z80 side I have a PIO that in this case just talks to the LCD.

How it works.

The Arduino begins by configuring a PWM clock signal to the Z80.
Setting Reset low on the Z80. This also enables shift out on the shiftregisters.
Writes Z80 code from HEX values extracted from a Z80 binary to the sram starting from adress 0.
The Z80 code array with HEX codes are currently generated with a pc program that outputs a C header file that is used with the Arduino sketch.
When the code copy to sram is completed it takes Z80 reset to high, which also disables the shiftregister output, and the Z80 startup by reading from sram.
The Z80 is now running and the only thing that the Arduino is used for is now the clock.
In the photo you can see it running code that drives the PIO to display text on the LCD.


Hi Micheal,

If your still with the Forum, I think your work is under appreciated.

Well done, Alan0

I learned assembly on the Z80 in college. It was a basic digital electronics class that was required for computer science majors. I loved that class, and I was so excited when I discovered the Arduino - an inexpensive and easy way for me to get back into that again 32 years later :).

I taught myself Z80 assembly language on a Sinclair Spectrum in the late 80s. I have an unused Z80 and would love to know more about your project. A schematic would be helpful.

I learned Z80 assembly on a TRS-80 in the late 70's on a Radio Shack TRS-80 Model I. My Arduino UNO has more ram than my TRS-80 did!

A schematic and code examples would be great!

What clock speed are you putting into the Z-80? I think the TRS-80 ran at 1MHz or there about.

Very COOL! :slight_smile:

Nice job, you should write it up as a presentation and put it in Exhibitions/Galleries.

Tom.. :slight_smile:

I like this idea of interfacing to old chips like this. Cool!

I had an MPF-I.

Alas, "had" being the operative word. I took it to work to show someone, forgot to take it home, and went on annual leave. It was gone when I got back.