
I have a lot of Retroshields here at home because it is a nice way to play with a microprocessor without having to build a complete computer. This Retroshield (that is available in this webshop) is a little different from the common ones, this one covers the whole Arduino Mega, but has the advantage that it uses no SMD components (the small one does) and it has an experiment area and a connector to connect a SPI device.

This is my build, as you can see it is quite simple to do. This shield adds an RCA 1802-processor to your Arduino Mega 2560 and with the provided code it will run a lot of 1802-based software from the good old 70s. This board is based on software and designs by Erturk Kocalar, there is a small prototyping area to the left side that you can use to a button, an extra blinking LED and an I2C header was added, perfect for those cheap 0.96″ I2C OLED displays.

Above is a screenshot of the startup screen of the Retroshield. This board is completely compatible with the small board and all the software will run on this board as well. The software contains a Monitor program, a Tiny basic and a full basic implementation. As it is all in the Arduino sketch you can add whatever you want or modify it, the software is on Github and open source. You can find the link to the Github project at the bottom of this page. I had some fun building this and playing with the software.
Sourcecode of this project
Link hardware: https://github.com/tebl/RetroShield1802-PCB
Link software: https://gitlab.com/8bitforce/retroshield-arduino
Links about the RCA 1802
- My page about the RCA 1802 processor – https://www.heinpragt.nl/?p=2924
- Wikipedia page about the RCA1802 – https://en.wikipedia.org/wiki/RCA_1802
- Page about the RCA1802 with a lot of documentation – http://www.decodesystems.com/cosmac/#cdp1802
- The 1802 Membership Card project – http://www.sunrise-ev.com/1802.htm
- Information about the 1802 Cosmicos computer – http://retro.hansotten.nl/radio-bulletin/1802-cosmicos/
- Nice page about the RCA 1802 – https://academickids.com/encyclopedia/index.php/RCA_1802
- Datasheet of the RCA 1802 processor – https://www.heinpragt.com/download1/CDP1802ACE_datasheet.pdf