This machine is a reconstruction of a hobbyist built machine from the early eighties. It came to me in pieces in amongst a lot of other gear, so it wasn’t obvious to me that there was a complete computer there at all.
I had already rediscovered a Cromemco based computer which used half a dozen of the 29 S-100 cards that i’d received. I also had a rack, some 8″ drives, and a lot of 8″ disks which i had previously imaged.
Many of the disks were labelled as being Jade, and there was indeed a JADE DD Floppy Disk Controller amongst the cards. There were many more disks that used the JADE format.
There was also a Versafloppy II Floppy Disk Controller card, for which there were also a number of disks.
These were all CP/M disks so i was looking for a 8080, 8085 or Z80 processor board. The candidates were a Cromemco SBC which wasn’t a great fit with CP/M or a CompuPro 8085/88 CPU card which would work.
I also expected there to be some I/O and a card for a boot ROM. And RAM of course. There weren’t a lot of clues from the cards themselves.
Fortunately there was a disk labelled “Jade System BIOS Development which contained some assembler files for the CP/M bios and the boot ROM. At this point, i ruled the Versafloppy II out.
The boot ROM code had some comments identifying key components (8251, 8255 and 8253) on a W/W card. Once i found the card with that combination of components, i realised that W/W stood for wire-wrap. It was a hand-crafted board. It also has a speech synthesiser chip!
Looking at the chassis, i could see that the wires dangling from the back panel married up with empty sockets on the board.
A little while later i realised that there a couple more ports which may belong to this unidentified card:
It has a real-time clock on it.
I had several memory cards that could potentially be used, but given that the CPU card is capable of addressing more than 64k, i started with an Intersystems 256KDR.
This card is probably overkill, and i may swap it out in the future.
I do have an EPROM card, but it is made for 2708 EPROMs which i can’t program at present – i would need a new programmer.
Instead, i built a new card using a modern S-100 prototype card.
These cards for the basis for the system.