...since someone or something (was it done in an automated fashion at the factory?) had to do it to begin with.

Tore, If I understand you correctly, you are saying that major subsystems were added to the CPU and wired into the backplane by a former user, who removed these components without regard to its effect on the operability of the machine before you came into possession of it. That wouldn't surprise me at all. Many academic and lab shops did extensive custom modifications, like the famous BBN paging box on the Tenex KA-10s. If this is the case, then clearly you've got your work cut out for you. I would caution you against assuming that the maintenance manual is complete and accurate for your machine. These machines went through multiple revisions and field ECOs during their lifetime. There was a set of field maintenance prints issued for the specific revision that a customer had, which was then kept up to date with the machine. (At least this is true of the Straight-8 of similar vintage.) It is even possible that you will not have exactly the same cards as documented in the manual, so certainly check this before pulling any wires loose! Consider an ECO that requires an extra gate or two, for example. I think the most prudent course of action would be to leave the existing wiring in place for now, but to carefully trace out what modifications were made and note what wiring has been added and removed. The pictures of the machine show some wiring of a different color -- frequently new wire added during customer modifications or ECOs would be a different color precisely to make it easier to identify, so you might want to see if that theory checks out for your machine. Once you understand the nature of the modifications in detail, then you can undo them. Wire-wrapping is tedious, so you might as well avoid as much of it as you can. A young guy like you might be able to trace out the wiring by eye, with a little help from a continuity tester (cards out for this unless you have a "zero current" tester) and a probe to displace wiring that is obscuring your view. A better bet might be a "fox and hound" type device such as described on Aaron Nabil's "Tools and Tips" page: http://pdp-8.org/tools.html If you have any contact with the original owner, it would definitely be worth tracking down any information that you can dig up on the nature of the modifications, even if the detailed wiring changes are not documented, just to help you make sense of them and sort out what were customer changes and what might simply have been manufacturing differences and ECOs relative to the maintenance manual that you have. As mentioned by others, it would indeed be a good idea to pull all of the cards and clean the connectors. I would recommend labelling all of the cards first with their locations, and not assuming that cards of the same type are interchangeable. Some of the flip-chip cards may have trimpots or jumpers that are adjusted for their particular role. Good luck! --Bill

http://rallar.dynalias.com/sintran/history/history.html

I can't read a word of Norwegian, but from the pictures, it appears that Norsk Data made quite a number of interesting machines from 1967 into recent years.