Re: [CAD_CAM_EDM_DRO] Cnc PCB drilling machines z axis linear pot

Paul Amaranth wrote:

> When production wirewrap was the state of the art for construction
> practice, they did have cnc type machines to build the boards. I
> have a couple of boards machine wrapped from a computer system from
> the late '70s. I saw a picture of one of the wiring machines in action once.
>
> You can wirewrap boards into the low MHz range, but things start getting
> flakey above that. Anyone know what a reasonable top-end is?

National Advanced Systems (a division of National Semi) made IBM 370
plug-compatible mainframes with about 10,000 chips of 100K ECL
completely on Augat wirewrap boards. They had clock rates on the
order of 50 MHz or so, I think. As far as I know, most of the clock lines
for the individual chips were just wire wrapped. They may have had
dedicated traces and receivers for global system clocks on each board.

Some MIT guys were able to buy up these machines for $25 - $100 when
one of the big computer resellers/leasers went belly up in the '80s. I'm
not sure if even the MIT dorms could handle the power and cooling those
beasts needed, however!

I did some tests on ECL signal transmission on wirewrap boards, and things
looked quite good well into the tens of MHz. This was with 120 Ohm terminated
lines, I think, running diagonally across a 12" square board, across some
length of wirewrap backplane, and then across another board diagonally.

Jon