Reverse engineering vintage PCBs

tony duell ard at
Thu Jan 8 14:45:21 CST 2015

> My personal gripe is with the schematic diagrams that look like visual
> netlists--ICs with terminal points marked, but no or few actual wires
> drawn.  Downright hell trying to figure out how the thing works.

It's difficult. Long 'wires' that go from one side of the schematic to the other
can be very hard to follow too. I think it helps if the schematic is drawn as a 
set of functional blocks with the inputs and outputs given sensible names.

But anybody who draws an SR flip-flop as anything other than a pair of 
NANDs (or NORs) with the obvious cross coupling shown as wires is 
going to get a LART... (OK, a cross-coupled AND and OR is OK if applicable).

Taste in schematics is obviously a very personal thing, but in general I find the 
modern CAD-produced schematics to be a lot harder to follow, for many reason
than the older ones.


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