I’m excited to announce a very cool project for retromaniacs:
- RetroShield is an 8-bit microprocessor daughtercard for Arduino Mega.
- A real 8-bit microprocessor executes programs while Arduino Mega emulates RAM, ROM, and basic peripherals.
- No need to build complex circuits, or burn EEPROMs :)
- Currently supported microprocessors: 6502, 6809, and Z80.
- Existing Arduino shields can be used to extend the capabilities, i.e. SDCard.
- You can learn how microprocessors work, or try assembly programming or run some of the old operating systems/programs without building complicated circuits.
- Arduino Mega drives a REAL microprocessor
- Microprocessor runs at ~95kHz.
- RAM : 4~6 KB (using Arduino Mega’s 8KB RAM)
- ROM : 200+ KB (using Arduino Mega’s 256KB FlashROM)
- UART emulation (using Arduino Mega’s serial port)
- Compatible with existing Arduino shields such as LCD/Keypad or SDcard.
- Schematics, PCB, gerber files are available at RetroShield-HW.
- I used GEDA gschem & pcb first time to release a board (read my thooughts on this experience).
- Hardware design files are open-source.
- RetroShield 6502 Theory of Operation
- RetroShield 6809 Theory of Operation
- RetroShield Z80 Details (work in progress)
Basically, software running on Arduino defines what hardware is available to the microprocessor. I put together the following samples. My hope is people will be able to add/contribute so we have many flavors of emulated hardware to experience.
- Apple I, Monitor + BASIC roms
- Simon6809, educational monitor w/ assembler/disassembler
- 8251 echo test, I am still searching for a simple monitor code. in the meantime, added this 8251 echo test code.
Let me know if you want to add a link to your Arduino code.
- Memory expansion board
- RetroShield for 1802 (check this out : COSMAC ELF Membership Card)
- Motorola 68008
- Intel 4004 (I see chips on sale on ebay)
- eeprom programmer (though unrelated)
If you want to suggest anything else, send me an email.
- I have some available at my store.