Reply to post:

It woz The Reg wot won it! Big Blue iron relics make it back to Blighty

John Geek

sigh, the /20 was the bastard stepchild of the system/360 lineup. it only has 8 16 bit registers, instead of the 16 32 bit of the rest of the 360 line, and its instruction set is very subset and incompatible. The /20 had 4-32KB of core memory, and you needed at least 12KB to run the DPS OS which wasn't very compatible with anything else in the 360 lineup. its a shame its not a 360/40, those could at least run the mainstream DOS/360

restoring that thing to full operational state is likely going to be a major project. they used DTL logic, and ceramic hybrids rather than integrated circuits, which IBM called SLT. The DTL logic can be either 0-3V or 0-9V. I know a retired guy who restored an IBM 1130 of the same generation a couple years ago, it was about a 2 year full time project to get it fully functional. Part way through it, the front panel lights started dying of old age, and they were an unobtanium 'grain of wheat' lightbulb, so he ended up having to engineer and fabricate a LED based front panel replacement

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