1 Nov
2001
1 Nov
'01
10:17 a.m.
ajp166 wrote:
Those parts were never cheap!
You can also use 74289s for the '189s. The '382s are an improved version
of the '182. A note, if you can tolerate a slower ALU you can omit the
'382s
and just use ripple carry.
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).
A sub for 74189s is some of the byte wide cache rams
from an old 386/486
PC as the faster ones were faster than the TTL 74189! You dont have to use
the full space of the cache ram though having it would make afor an interesting
register array.
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.
2) I am using the 486 cache chips as main memory in my FPGA prototype
32k x 12 bits.:)
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.
Allison
As it stands today I have a FPGA ( pat
pat pat ) that is configured to
have a similar
layout as the ttl design and this lets me play around with the
configuration. Mind you a
larger TTL CPU with lights and switches is more impressive. If you like
lights
and switches here is a neat link http://www.angelfire.com/scifi/B205/
'to the Bat Cave'
Ben Franchuk.
--
Standard Disclaimer : 97% speculation 2% bad grammar 1% facts.
"Pre-historic Cpu's" http://www.jetnet.ab.ca/users/bfranchuk
Now with schematics.