I thought I’d post a short update:

The Backplane adaptor boards have arrived and I have tested one. It works fine. I’ve posted the design files on the Project page. In case you missed the previous post, this new board allows standard interfaces to fit on the Backplane vertically as they would with the Spectrum or Interface One rear edge connector. Some interfaces will need to be fitted to the third of forth slot on the Backplane to miss the on board regulator.

The special project I’m working on has been a little troublesome. Making a few small mistakes on the first schematic didn’t help. One of the mistakes was to use a 16-pin DIP socket for a 14-pin IC. This meant that all the connections ‘rolled around’ the chip and meant that I had to make a patch to see if I could get the board working. This is when I discovered a further mistake that I had made in tracing the circuit. All the joys of reverse engineering!

I have now updated the board and have it working to a point. I think that either one of the ICs is faulty or I may have transcribed one or more other connections incorrectly. It is a fairly complicated circuit built on a home made two sided board with wire vias. Investigation continues.

Another development; My recreated SPEC-MATE stopped working. It took me a while to discover why it repeatedly crashed the machine it was attached to when the NMI button was pressed. It turned out to be a corrupted EPROM. This is despite having an opaque sticker over the exposure window. I think the EPROM was just suffering with age. Once I’d programmed and fitted a new one, it worked correctly again.