my prototype SCELBI-8B

Finally powered on. Still need to add and test memory expansion and memory card, but I can jamb instructions with the front panel. I’ll start checking out the memory as soon as I finish this post.

While wiring the backplane, I found that SCELBI made a change in the RDYN jumpering. Instead of jumping XA02 A-X to A-Y and A-Z, the 8-B instructions connect XA02 A-X to A-Z and connect XA02 A-Y to B-F. I’ll find out as the day goes on, if that makes stepping any more reliable. If so, it would make a good change for the 8-H, also.

The chassis was hacked together out of wood and sheet metal. I’m looking into finding a used Box and Pan brake so I can cut and bend my own chassis. The ten Bud chassis’s Corey had made for the 8H project cost $1000, and that left no room for profit, so he sold them at cost. Also, I want to make chassis for the expansion cards and power supplies. The whole thing just adds up to too much expense. Also if I had them made, when the batch is sold out, then future SCELBI builders are left without options, cause I can’t afford to buy ten and have nine sitting around for months.

my prototype SCELBI-8B top view

For the prototype, I’m just wiring up 1 input and 1 output bit, so I can download programs and use a terminal. Here is the back panel.

Minimal I/O prototype SCELBI-8B