ZX81 Homebrew Clone for Baffa-2 Project

Project codename "Baffa-81" is a set of boards to make a ZX80/ZX81 Clone for Baffa-2 Homebrew Computer

Similar projects worth following
Baffa-81 is a Sinclar ZX81 clone on Baffa-2 Homebrew Computer. It's based on Grant Searle's ZX80/81 Project, heavily inspired by Wilco2009's Board (Alejandro Valero) and my own experience after had built it (... and fixed some Zeddies). It uses Z80 CPU and Dual Clock boards from Baffa-2 Basic set and has 32KB RAM, 4K/8K ROM option (ZX80/ZX81) and allows you to use a PS/2 or original keyboard.

Baffa-2 is an educational and personal project with the aim of understanding how computers work through 80's 8-bit commercial machine designs. It has a modular concept with boards that can be combined to develop your own design and configuration.
More info:

This was my first design for Baffa-2 Homebrew Microcomputer project but I decided to prioritize a CP/M machine before. I had dedicated sometime to studying Grant Searle's ZX80/81 project and building the board designed by Wilco which has an excellent backporch solution using the LM1881 and went after other platforms.

After about 10 months, I decided to review and finalize the boards and try the solution. As I needed a new set of backplanes, I chose to design a cheaper version that is half the size and can be used in smaller projects like this one.

I am very grateful for the support provided by PCBWay that made the completion of this project possible.

This is a presentation video showing the initial tests: 

The video board implements the slow circuit and replaces the ZX81 ULA IC. A detailed explanation about it is at Grant Searle's website. Also it has a jumper to switch between nomal/inversed screen and 2 backporch options (Searle's white restauration and Wilco's LM1881 solution).

RAM/ROM Board allows you to switch between ZX80 4kb rom and ZX81 4kb rom 

I/O Board (Cassette and PS/2 Keyboard) adapts the Danjovic's Tek V2 solution to emulate the keyboard matrix using an arduino. It also can be used with the original membrane keyboard (SV1 and SV2 sockets - not soldered )

New Baffa-2 Backplane Lite

View project log

Enjoy this project?



Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates