Supercomputing adventures with a MegaST/4

[rubber_jonnie]

So is it possible to stack the boards one on top of the other to improve density?
If not then why have the sockets at all?

As far as I know, the cannot stack TRAMS. I *think* the sockets are so you can probe signals easily.

I kind of thought that would be the case, especially since the components are too tall to allow stacking, but wouldn't it be cool if you could

[dml]

I did see a post somewhere on an old Transputer discussion forum where they were actively talking about 'stacking Trams'. I don't know if I bookmarked it... will look later.

Anyway it seems unlikely because the serial links are just an RX/TX pair and if you stack them together the Transputers won't know which message is intended for which unit. Even if you had the software sort that out with a complicated multicast protocol, the link controller would lose packets on colliding signals.

But maybe someone thought of all that


I'll follow up soon with more progress on this thing...

[dml]

Great find. Several employees here are former inmos engineers who say they have old boards in their attics and I've been begging them to bring them in / loan or sell them to me. So far just a few pictures no hands on

So cruel of them I hope they change their ways and drop you some boards.

[dml]

The next incremental step towards desk-flames was to plug the thing into a VME backplane - one that is not designed for it at all - and see if I could find any compatibility problems with pinouts/conflicts. Especially the power hookups.

I beeped out various points and confirmed 5V/GND where it should be expected and nowhere it wasn't expected. I wasn't really exhaustive with that but it was 'good enough' for the next step.

I obviously removed all the TRAMs before taking things further in case of accidents. They were bolted down with extremely annoying nylon bolts with some 1980s version of nail-varnish-threadlock stuff. I got most of them off by applying IPA and cracking the varnish with pliers before attempting to remove them. A few 'died' in the process when I ran out of patience.

backplane.jpg (718.5 KiB) Not viewed yet

I powered the backplane from a 5V bench supply. The backplane has nice chunky power terminals with big bolts. That might come in handy later.

backplane-power.jpg (652.43 KiB) Not viewed yet

...especially since the backplane alone sucks more than an Amp just for termination.

vme-amps.jpg (342.62 KiB) Not viewed yet

Anyway nothing blew up yet and I could see power at the correct points on the ICs etc. Good for the next step....