https://github.com/and3rson/leo80

Z80-based single-board computer
https://github.com/and3rson/leo80

assembly lviv sbc single-board-computer single-board-computers z80 zilog

Last synced: about 1 month ago
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Z80-based single-board computer

• Host: GitHub
• URL: https://github.com/and3rson/leo80
• Owner: and3rson
• License: mit
• Created: 2023-07-17T18:12:51.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2023-07-29T23:43:12.000Z (almost 2 years ago)
• Last Synced: 2025-04-06T23:29:10.406Z (about 1 month ago)
• Topics: assembly, lviv, sbc, single-board-computer, single-board-computers, z80, zilog
• Language: Assembly
• Homepage:
• Size: 3.33 MB
• Stars: 4
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# leo80

Z80-based single-board computer

![Assembled device](./img/v1_ready.jpg)

![Schematic](./img/v1b_3d.jpg)

# 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

![Schematic](./img/v1b.jpg)

# PCB

![PCB](./img/v1b_pcb.png)

# Resources

- anycpu.org forum [thread](https://anycpu.org/forum/viewtopic.php?f=25&t=1060)

- Original [datasheet](https://www.zilog.com/docs/z80/um0080.pdf) (very slow download), or alternatively - archived versions on [my website](https://dun.ai/files/z80.pdf) and [archive.org](https://archive.org/details/um0080httpswww.zilog.comdocsz80um0080.pdf).

- Z80 interrupt vectors: https://www.smspower.org/Development/InterruptVectors

- SjASMPlus docs: https://z00m128.github.io/sjasmplus/documentation.html