Retroshield for Arduino Mega



I’m excited to announce a very cool project for retromaniacs:

Completed RetroShields:

My goal is to build a daughtercard for every microprocessor out there. This is what I have completed so far.

Microprocessor Emulated Hardware Software
Intel 4004 printer + kbd Busicom 141-PF Calculator (
Intel 8031 8031 + UART PAULMON2 (Paul Stoffregen)
Intel 8085 8085A + 8251 MON85 (David Dunfield)
MOS 6502 Apple-1 (6502+6521)
KIM-1 (6502 + 6530)
MON,BASIC,Cassette (Steve W)
KIM-1 (MOS Technology, Inc)
Motorola 6803 6803 + 6850 Bill Beech’s 6800 Monitor Code
Motorola 6809 6809E + FTDI Simon6809 (Lennart Benschop’s monitor modifed by Erturk)
RCA 1802 1802 + UART MCSMP (Charles J, Yakym)
Tiny BASIC (Tom Pittman)
RCA BASIC3 (Ron Cenker)
Signetics 2650 2650 + UART Signetics PipBug M20 Monitor Code
Zilog Z80 Z80 + 8251 Microsoft Basic (MSFT, Grant Searle)
EFEX (Mustafa Peker)

Arduino Mega 2560 Features:

Retroshield in action

Teensy 3.5/3.6 Features:

Retroshield in action

I built an adapter board for Teensy so we can get more RAM and faster clock speeds. Bonus is we get to use the same Arduino IDE for code development:

Design Files

All hardware and software is open source.

Upcoming microprocessors:

I’m currently working on the bold highlighted processors.

Let me know if you want anything else to be added to the list.

Kit/PCB Sales

License Information

The Force

RetroShield 4004 is released w/ Arduino code that emulates Busicom 141-PF calculator running the original ROM images.

6502 6809E Z80
RetroShield6502 RetroShield6809e RetroShieldZ80
1802 8031 8085
RetroShield1802 RetroShield8031 RetroShield8085
2650 6803 4004
RetroShield2650 RetroShield6803 RetroShield6803