MODCOMP II Rescue Revisited...

A number of you probably remember me "announcing" in Jan, 2007 that I had rescued a MODCOMP II/12 from a lab here in Silicon Valley. The link for that is below (sorry, it's slow - the pictures are large). http://bickleywest.com/modcomp.htm After a lot of work cleaning up both the CPU and I/O chassis I began checking out the system. It turned out that the I/O chassis was in pretty bad shape. I went back to the lab facility where I found the MODCOMP II - looked through several more buildings - and found another lone MODCOMP II I/O chassis. I went through the "salvage" process again - and finally picked it up about a month ago. It was in a lot better shape than the original I/O unit. And the really great news - it was an identical configuration to my original I/O chassis. After cleaning it up, doing all the usual capacitor, power supply checking - I powered it up - and everything "looked" good - and no bad "cooking" smells ;-) I cabled up the CPU and I/O unit, powered 'em up - and to my amazement the front panel controls seemed to work O.K. I then did the usual hand memory tests - and core memory worked O.K. every location I tested. I then wrote a bunch of small diagnostics (in machine code) - and found that I/O was not easy to code - but I did enough to check that the console in/out ports worked O.K. Today I loaded diagnostic monitors, and diags - and most of the system - including I/O is working! The really good news is that all 64K (words) of core memory passed the long manufacturing memory diagnostic - which even tests for "hot cores" failing. It's been months in the making this critter come alive - but it sure feels great when the diagnostics tell you that you are on the right track :-) Cheers, Lyle -- Lyle Bickley Bickley Consulting West Inc. Mountain View, CA http://bickleywest.com "Black holes are where God is dividing by zero"