26 Feb
2008
26 Feb
'08
8:28 p.m.
From: "Roy J. Tellason":
On Tuesday 26 February 2008 12:40, Vincent Slyngstad
wrote:
Cool!
Depending on what you are working on in the Mxxx series flip-chip
line, there's a bunch of 74Hxx, quite a bit of use of and-or-invert
(7450, 7453, H50, H52, H53, H55) and expander gates (7460, H60, H62),
7482 adder, 74181 alu, 74182 look-ahead carry. If you are specifically
building an 8/L, you can get away with a subset, but I know off the top
of my head that the M220 card (major registers and ALU functions) uses
7453, 7460, 7482, and I believe 74H40 chips (as well as the 7474, which
isn't too hard to find).
Of course, you could redesign the flipchips to use more modern stuff,
but then you might get into a semantic quibble about whether it was
really still a PDP-8/L :-). And you probably still need a fair number
of 7401's or PALs or whatever to replace the and-or-invert gates and
arithmetic stuff.
I have some of these components, but the H5x and H6x stuff I mentioned
I've had trouble sourcing even a couple of. You can also often get
stuff for prices like $5 per chip, but that wouldn't be really practical
if you were trying to build an entire replica CPU out of them.
Vince
Generally, I think the 8/L backplane is a more
promising starting
point, though it lacks the cachet of being all-transistor (and
the DEC modules use dated, hard-to-find TTL).
What TTL are you calling hard to find? Just curious, as I might
have some of it on hand here...