leo80

Z80-based single-board computer

Design considerations

• $0000-$7FFF - ROM.
• $8000-$FFFF - RAM.
• Address decoding with ATF16V8.
• Using perfboard for this, so trying to keep it small & simple - will be adding more fancy things later (LCD, UART, etc).
• Simple 8-bit input through '244 tri-state buffer.
• Simple 8-bit output through '273 flip-flop with 8 LEDs for visual output.
• I used AS6C4008 in schematic since it's included in Kicad parts by default. I have various SRAM chips available. Same with W27C512 EPROM.

Schematic

PCB

Resources

• anycpu.org forum thread
• Original datasheet (very slow download), or alternatively - archived versions on my website and archive.org.
• Z80 interrupt vectors: https://www.smspower.org/Development/InterruptVectors
• SjASMPlus docs: https://z00m128.github.io/sjasmplus/documentation.html