Extract from a Jacquard brochure
Andy Alder reports:
The motherboard PCB technology was multi-wire which I've never seen
before or since, plated-through holes were inserted into the PCB and
very thin bare copper wires were wrapped around them. When one layer of
wiring had been laid down a thin plastic sheet was layed on top of that
and another layer of wires layed down. I think it was 4 wire layers on
each side plus the ground and 5V planes.
On the J100 there was also a J300 with a beefed up CPU card and faster
Tom Morgan's memories:
I worked as a test technician on them when they were first developed. I
worked on the J500 and J100 as well as the parking lot control system
they built at the Dallas-Ft.Worth airport. I worked for them in 1973-74
and again 1978-79 before leaving So. Cal for the Silicon Valley.
The J500 was unique in many ways since it was the first or one of the
first desktop mini-computers. It used the AMD 2900 series processors in
the bit-slice design which made it very fast for the time. As noted in
the write-up, the buried wire design was truly unique, but it kept the
thickness of the motherboard to a reasonable level. One of the
engineers told me that the board would have had to be 20+ layers to
equal the circuit density of the buried wire board. This compact design
came at a price for test technicians who had to fix things though,
because re-working the board was a bear.
The system had a large amount of on board memory at the time of 128K and
the entire computer was on one PC board, which mounted on the bottom of
the case and all the disk drive,floppy and other peripheral controllers
were integrated into the main board. Neat stuff for the time.