Topic: Making new SSM IO-2 Boards
Date:  2018 JUL 02
Reproduction Boards Now Available!
We have bare boards and parts kits available through our Tindie store:
The Solid State Music IO-2 is one of my favorite S-100 boards: I’ve used it to build a debug board, a 1702A ROM/2101 RAM board, and a power-on jump board, as well as other projects that I haven’t documented online. Its versatility comes from the minimal address decoding and I/O laid out in copper – the rest of the board is prototype space. It’s usually the board I grab when I want to quickly interface a project to the S-100 bus. Unfortunately, vintage IO-2 boards are difficult to find. They’re also usually populated with someone else’s old project. While cleaning up a vintage board for reuse, I decided to fully strip it down and send it to Mile High Test Services for high resolution scanning. This allowed me to make reproductions of the board, here’s a first run prototype, built up as a simple parallel I/O board:
It’s hard to find a board house that will run circuit boards with colored FR-4, so I tried an experiment with this run: I created a solder mask layer that exposes all of the traces, covering only the spots that would’ve been bare FR-4 if I had run the boards with no solder mask. As seen above, I think the effect worked nicely. The board doesn’t look exactly like an original, which I sort of count as a bonus anyway, since it would be harder to pass off as original by an unscrupulous seller. Here’s a closeup of the SSM logo etched in the copper in the regulator area, even this part came out alright:
With the prototype design tested and confirmed, it was time to do a small production run. I knew several people from the s100computers.com Google Group, Altair Computer Club, and various other groups would want reproduction boards, so I ordered a large enough run to make hard gold edge plating affordable. Hard gold is critical for long term durability of edge connectors, ENIG is not sufficient. Here are the results:
As with all of my reproduction boards, this one has a note stating it’s not vintage:
The first one I built up became an 8-bit LED output register:
The wiring was done with different colors from 25-pair telephone wire:
Just as with the prototypes, the production boards work fine! If you’re interested in getting your own reproduction Solid State Music IO-2 board(s), see the links to our Tindie store at the top of this writeup. Bare boards and full parts kits are availble. If you’d like something custom built on an IO-2 board for your system, please contact us and describe what you’d like built – we’re happy to build custom interfaces!
S-100 interfaces hacked