William Donzelli aw288 at
Thu Jul 7 07:53:47 CDT 2005

> I don't see how anything could be more documented than having the complete
> engineering drawings of the whole machine. And that's what you normally
> got on old DEC machines.
> That's what I have of the PDP-11/70. Full drawings of every curcuit in the
> machine. And then I have all the technical manuals for all subsystems that
> document things in a more text-like manner as well.

With IBM stuff, you get multiple drawings of every circuit of the machine.
The basics are the ALDs (Automated Logic Drawings) - these are the printer
generated, hard to read things that are the most detailed (all gates, all
connections, all pins labelled). Then, to make thing easy, IBM had more
traditional drawings, using nice art - still IBM specific, but much easier
to read. Then there are (many) flow charts, timing diagrams, sometimes
scope shots, and of course, warnings on where not to stick your tie.

By volume, I would say IBM docs are two to three times larger than DECs.

William Donzelli
aw288 at

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