Z80 Computer

This is a simple Z80 computer. It's being worked on so the specs will hopefully get better and the OS will improve. I'd chiefly like to run the CPU at the full 10MHz.

The CPU is only running at 2MHz as the graphical LCD is comparatively slow (requiring a 900nS read or write cycle) and slowing the CPU down was easier than building the state machine to insert Z80 wait states.

Current Hardware Specifications

Software Features


I recorded this brief video to discuss some of the problems in the design.

YouTube video of Tetris

Journal Posts

The following journal posts have a lot of pictures and information on the project. They are arranged in ascending date order, so start at the top and work your way down if you want to follow the progress!


Here are some more photos of the computer's hardware. They are not the most up-to-date photos, but should give you a rough overview of the hardware involved.

The complete computer in action. Click for a larger image.

Memory board, with Z80 CPU, 128KB Flash EEPROM and two 32KB SRAM ICs. Click to toggle labels.

The I/O board, with LCD pin header, control port and two PS/2 ports. The I2C bus driver circuit is also present.

Two 8-pin I2C chips; a DS1307 real-time clock with 32,768Hz crystal in the foreground with a 24LC256 32KB EEPROM behind it.

Early version of the hardware with the Z80, 128KB Flash EEPROM and single 32KB SRAM ICs on breadboard.

Early LCD test using a PICAXE-28X1 microcontroller.

Early RAM test using a PICAXE-28X1 microcontroller to record and play back an analogue signal.