mgh80 - "The Arduino of the 80s"

This 5 chip Z80 single-board "computer", is a very simple Z80 based "controller" with 8255 for I/O plus a "Z50Bus" expansion connector. I created it to kick-start my Z80 experiments - breadboarding is fun, but sometimes you want the basics to "just work" so you don't have to troubleshoot loose wires :)

Features an option to use a local crystal-based oscillator or oscillator module. There is an onboard selector to choose between 27c256 EPROM and 28C256 EEPROM.

Onboard address decoder:

• ROM at 0000h - 7FFFh
• RAM at 8000h - FFFFh
• IO at 00h (IOPortA)
• IO at 01h (IOPortB)
• IO at 02h (IOPortC)
• IO at 03h (Control)

A few solder jumpers allow disconnecting various onboard options (if you for example want to provide an external address decoder)... In the basic configuration you should link (with a solder blob) the following:

• JP1 - enable internal CLK source
• JP2 - enable internal IO(8255) address decoder
• JP3 - enable internal ROM address decoder
• JP4 - enable internal RAM address decoder
• JP7 - set 8255 reset pin to GND (bypass R5)
• JP8 - enable onboard LED for port A0 on the 8255
• JP9 - enable onboard IO_WR singal

Simple "blinky" program source (.asm) included and a compiled hex files (.hex) for 27C256 EPROM (or my EPROM emulator). It will toggle all lines of port A a few times a second.

Get your PCBs from PCBWAY

A few component kits are listed on eBay

If you found this helpful and you like the work I do, why not buy me a coffee, thanks ! :)