6 Sep
2007
6 Sep
'07
12:31 a.m.
On 9/5/07, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Don;'t you mean 7483 here? ...
The 74283 is a 4-bit adder with a more sane pinout (and corner supply pins).
Ah... good to know. The PDP-8/L and -8/i have a 7483 on each M220
card, but I remember seeing either a 74283 or, if it exists, a 74183
in the design for that PDP-8/i work-alike I mentioned here a few weeks
ago. The difference, I would guess, is probably that the designer of
the clone didn't want to fiddle with an older, odd chip.
I should probably find a source of a handful of 7483s since I have a
small stack of dead M220s. I don't know what's wrong with them yet
(probably dead 7474s if the rest of the machine is any indication),
but I'd hate to trace it to the adder and have no spares on hand.
I did not realize it was a strange-power-pin part. I would have
figured it out eventually, but it's best to be forwarned.
-ethan