DEC bus transceivers
jnc at mercury.lcs.mit.edu
Wed Oct 26 06:38:02 CDT 2016
> From: Guy Sotomayor
> Secondary chip marke[t] (only reputable vendors).
I'm a little more willing than Guy to troll in disreputable waters (I bought
1K DS8641's from a source in Hong Kong), so I have this:
which has a bunch of special circuits on it to test chips to make sure they
meet specs; e.g. the large potentiometer is so I can vary the input voltage
to see where it switches from 0 to 1, etc.
> From: Paul Koning
> it would be odd to have one; I can't think of anyone who would expect a
> PDP11 to work with part of its devices powered down. For one thing, if
> the box with the terminator loses power
Forget the terminator - as Jon Elson also points out (his email appeared
while I was creating this one), any device which uses interrupts, if
un-powered, won't pass grants.
> From: allison
> Bottom line is someday there will be no DEC parts and what then? I
> reserve DEC parts for repairing defunct boards for new and unique build
> it would be a waste of scarce material.
For actual DEC interface IC's like DC003's, sure. Those are hyper-rare.
But DS8641's are available in the 10's of thousands, there's no earthly way
we could use them all on repairs. Yes, when they run out, we'll have a
problem - but I plan to cross than bridge _if_ and when we get to it.
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