This is a board we did at Peer Protocols. It captures narrow 10 megatransfers / sec traffic on an 8 bit 50 pin bus.
It was an early design and only had the narrow connector sticking out the back of the PC, so you had to put it in the middle of the bus. Not an unusual place to wire such a board, but sometimes lead to fun trying to have a fully functional bus.
Termination of course had to be at the ends, and frequently in early days there was no active termination for the ends of narrow ribbon cables.
The top board, was from a development system, the Peer 7000. It was a narrow and wide general purpose SCSI development system. It could be loaded with firmware to be either an initiator or a target in any scenario. The fact this customer had two of them, and they have the differential back end means it was a very high end site. That they had the 0500 capture card meant they were likely doing narrow development.
The connector on the top of the 702 board was for suppling power for the differential to single end conversion. Differential in and out was on both connectors. The black 50 pin connectors are connected bussed together, and allows you to do a true loop thru. The rear wide 68 pin connector allows you to do wide 16 bit bus loop in and out.
The second board shows the one 68 pin connector on the bottom of the board. The photo above doesn't quite show the one which faces with the connector axis parallel to the board.
The rear connector would be fastened to the 7000 board. The 7000 set was a dual board set with 1mb of memory and a 80186 co-processor which ran on the ISA bus. There was a 512 byte common ram mailbox between the host PC and the 7000 board for interaction.
The 7000 ran autonomously once it was configured. Usually only thing that would go thru this bus to the host might be for memory to allow a large emulated target device (tape or disk).
We never did drivers to use the 7000 at either end as a SCSI controller. It did do a pretty good job of emulating a small Streaming tape which was similar to the Archive ST-150. It didn't typically have much memory capacity, since it used host memory for its emulated tape, but it did a good job of fooling such as SCO and other systems which thought they were actually talking to an Archive drive.
|702 board Differential option for 7000 system|
|back of 702 board|
|Peer 0500 capture card|
|Far end of 0500 capture card. PALs are for memory control|
|Main SCSI bus decode logic, near input to board|
|Additional shot to get overlap of two shots|
|Rear of 0500 capture card|
At Irvine Computer, we used Al as a contractor to do our PC boards and at the time, he had purchased a full Gerber system with scanner and layout and printer.
The main business he had was doing layout with a dedicated workstation called something like IRIS or IRIX (not SGI) which was a dedicated system for doing board layout. Those workstaitons rapidly took over the main business at the time we did business with him (mid 80's) at Irvine computer.
Peer Protocols used him for board manufacturing, and if I read this board right it was a 94 (1994) board.