classiccmp-digest V1 #761

From: Allison <ajp166_at_bellatlantic.net>
Date: Fri Nov 2 07:17:39 2001

From: Ben Franchuk <bfranchuk_at_jetnet.ab.ca>

>If the 74289's are the non inverting 16x4 rams I would use them. I plan
>to use 74ls382's (the ripple carry alu's).


The 74289 is also the same part/pinout save for instead of open collector
they are
tristate outputs.

The 74382 is not an ALU, it's a carry look ahead generator. The 74381 is an
ALU.

>Can't do that for three reasons
>1) I am use a 16 x 12 ram ( 3 chips ) on two boards for a 8 x 24
>register array.


Not enough reason there, so you dont use the full byte width.

>2) I am using the 486 cache chips as main memory in my FPGA prototype
>32k x 12 bits.:)


So the cache rams are easy enough to find more.

>3) This was a TTL design on paper of what a computer designed in the
>early 1980's could have been like. That rules out 2901 bit slices.


BZZZT!!! By ealy 1980 the 2901 was already passe', as were TTL cpus.
I presume by that you really meant early (very early) 1970s as the 2901
is a 1970s part.

Also the 2901 is directly traceable to 74181, 74189 like parts.

>configuration. Mind you a
>larger TTL CPU with lights and switches is more impressive. If you like
>lights


I already have a real PDP-8. ;)

Allison
Received on Fri Nov 02 2001 - 07:17:39 GMT