A modernized approach to the PJRC 8051 dev board

I think this qualifies as Retro Computing; I’ve been interested in the PJRC 8051 dev board for a while but it has been out of production and/or not available for several years.

8051 Development System Circuit Board (pjrc.com)

I decided to build my own with some adjustments and modernizing the design somewhat. I would like to use it as the base for some future projects. Plus, I am interested in MCS51 and specifically the 8051/8052.

My prototype worked out surprisingly well and works great. There were a couple of “gotchas” in the build but nothing insurmountable. It runs PAULMON2 unmodified plus there are several pieces of software to test IO devices plus Tiny BASIC. The prototype is here:

duodyne/SAB80535-Dev-Board V1.0 at main · lynchaj/duodyne (github.com)

Based on the lessons learned from the prototype, I am designing a follow on board with greater IO and (I think) a better layout and design.

duodyne/SAB80535-Dev-Board V1.1 at main · lynchaj/duodyne (github.com)

I have a spare V1.0 board available so if anyone else is interested in MCS51 and would like to make their own, please let me know and I’ll send you the spare board.

Thanks, Andrew Lynch


This looks pretty cool, and with the 87C52 shown, it looks like it should be able to run BASIC-52.

I would be interested in your extra board; how much would it be to ship it to 15644 (Jeannette, PA - outside Pittsburgh)?

Sure, no problem. Just send me your shipping address by private message and I’ll send it to you. There is no charge or cost. The board is free and I’ll cover the shipping because you’re in the US and it’s relatively affordable.

The PJRC 8051 dev board rev 5 used an 87C52 MCU, however, my SAB80535 dev board used a SAB80535 which is 8051 compatible but somewhat different and required some adjustments. The main difference is the 87C52 has 8KB of internal ROM and requires programming (OTP, I think). The SAB80535 does not have internal ROM which necessitates the use of external Flash ROM and an adjustment to the memory map. Nothing too severe since I was able to make all the software work (PAULMON2, Tiny BASIC, various utilities, etc.)

Here is the GitHub repository with all of the technical data.

duodyne/SAB80535-Dev-Board V1.0 at main · lynchaj/duodyne (github.com)

Here is the list of findings from the initial build and test of the V1.0 board. These have been addressed in the V1.1 board I am currently working on (scroll down about 3/4 of the way down to the SAB80535 section)

duodyne/!Initial Build and Test/!initial build and test.md at main · lynchaj/duodyne (github.com)

Thanks! Andrew Lynch