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.
You can find more detailed project description on my website mygeekyhobby.com
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.
In the "Monitor" folder, you will find sources for a monitor ROM — the bare-metal firmware that boots up, gives you a command prompt, and lets you inspect/modify memory, set breakpoints, and run programs.
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! :)
