2024/02/28 - Ran out of all stock. I'm working on getting a new batch built. Stay tuned.

My Brain-In-A-Jar Project

• A daughtercard with a real 8bit microprocessor, plugged into Arduino Mega.
• Arduino Mega emulates system hardware such as ROM, RAM, I/O devices.
• Real microprocessor executes code.
• Clock speed is about 115kHz, (please see note below).
• 200KB ROM space available in Arduino.
• 6K RAM available in Arduino (can be expanded to 128KB - see my blog).
• Any existing Arduino shields (LCD, SDCard, etc.) can be used to add new features.

Please note this RetroShield will feel very slow with Arduino Mega: 1) 1802 itself takes 8 to 16 clock cycles for most instructions. 2) Software bitbangs UART over Q and EFx pins and Arduino implements soft-uart on these two pins. I'm adding support for my Teensy Adapter for RetroShield for faster clock and more memory (256 KB RAM).

What can you do with it?

You can run the following:

• MembershipCard Super Monitor Program by Charles J, Yakym Copyright 2015.
• Tiny Basic by Tom Pittman Copyright 1982
• RCA Basic Level 3 v1.1 by Ron Cenker, Copyrighted 1981

Or design your own hw platform in Arduino.

What do you get?

Three options:

• Assembled and tested board w/ microprocessor*
• Kit for you to build: PCB w/ surface mount parts soldered + microprocessor + socket/header/LED
• Bare PCB w/ surface mount parts soldered. (You supply rest of the parts)

NOTE: ARDUINO PICTURE SHOWS 6502, BUT YOU WILL GET RETROSHIELD 1802.

Why did you make it?

First, I have been building SBC's with old microprocessors since high school. For every SBC, I had to spend time wire-wrapping the ROM, RAM, peripheral chips over and over again. Then it was more hassle to expand the SBC. I am now lazy; Arduino Mega is capable enough so I now do my wire-wrapping in software :)

Second, I wanted to give back to the retro community. So all hardware and software design files are open source.

What makes it special?

• My goal is to make a daughtercard for every 8-bit microprocessor out there. so far I built six (6502, 6809, z80, 8031, 8085, 1802).
• I got chips for 4004, 4040, 8008, 8080, 8088, 2650, 8X300, 6800, 6803, 68008, F8, SC/MP, 6100, etc. So these are in the pipeline.