6 Sep
2007
6 Sep
'07
7:23 a.m.
On Wednesday 05 September 2007 19:31, Ethan Dicks wrote:
On 9/5/07, Tony Duell <ard at
p850ug1.demon.co.uk> wrote:
Are 7474s problematic for some reason? I seem to remember having a bunch of
those, but I think in storage...
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.
This seems to be as good a place as any to mention that I've got as many of
those "generic" numbers as I could find any data on, along with the
datasheets, here:
http://www.classiccmp.org/rtellason/by-generic-number.html
Along with other stuff elsewhere nearby. :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin