A quick update on status of the reproduction SCELBI project. The cassette read card is about 98% done. I could get boards made today, but before pulling the trigger, I’ll see if tweaking the layout a bit in a couple of places will make it match the original layout a bit better. I have obtained some audio files made on the tape interface of an original SCELBI, so I’ll be able to try testing it, without having to build the cassette write card.

I’ve started on the cassette write card PCB layout. First step of the process is to position components to match the component placement of the original card. This is largely done, but I’m going over positioning a few more times before laying traces. It’s best to get component placement as accurate as possible before starting on placing traces. Once you start laying traces, moving components around becomes a bigger effort.

There are a couple of unusual components on the write card. There is the SN72741, which is a single LM741 opamp in a 14 pin package. In looking around, those are scarce, but still can be found. There also is a relay in a DIP package, but like so many electo-mechanical components, it looks like those are still made. The relay is used to enable remote control of the tape drive. Some tape drives of the time had remote control for on/off.

As far as supply of PCBs for the main computer goes, I’m down to one complete kit in stock. This can be either the 8B or 8H. To be a little clearer, I only have one each, of the four boards that are in common between the 8H and the 8B. When this set sells, I’ll reorder those boards that I am low on, but it might take as long as a month or two to restock.

keep on vintage computing…