2 Jun
2006
2 Jun
'06
5:40 p.m.
On Friday 02 June 2006 08:12 pm, Tony Duell wrote:
Have a look at
http://www.classiccmp.org/rtellason/by-generic-number.html
and search for the word "expander" with your browser, you'll find as many
as
I've been able to find mention of, and not just TTL either.
Early
7400-series TTL had the 7450 and 7453 AND-OR-INVERT gates that
could be explanded with another 4 inputs via the 7460 dual 4-input
expander. I'd hate to own equipment now that used some of those that
required replacement--they must be very difficult to find.
There were at least 2 different expanders, I forget the number of the
other one. The HP98x0 machines use these gates as the input
selectors to the
bit-serial ALU (and I think to the T register (memory data register)). I
did have a 74H52 fail in one 9810 (that's an AND-OR gate), fortunately,
not much of it is used in _that machine_ and I could dead-bug in a
74LS51. That wouldn't work in the 9830, or I assume the 9820 (not looked
at the hardware of that machine yet, next project) as those use rather
more input sections of the AND-OR gate.
Speaking of 74H stuff, I have a fair box of chips here that I pulled out of
the boards of a Burroughs B500 that was scrapped. Almost all of these are
"house-numbered". Does anybody know where there might be a list that crosses
these over? I found only one or two that had 74H numbers on them, and I
think in maybe one case it had both...
--
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