Hi Tim and all,
At 04:51 PM 10/3/98 -0400, you wrote:
Why not go for a bit-serial (aka 1-bit) CPU? It's
an extremely classic
design, and is certainly the way to go to minimize total transistor
count.
Didn't Motorola make a 1-bit cmos microcomputer? Cannot remember it's part
number. I remember Turning machine articles in various places. One is "The
Armchair Universe" by A.K. Dewdney. It is a collection of "Computer
Recreations from the pages of Scientific American Magazine".
I've got some plans of designing a computer
this year. I'll probably
get my feet wet with a simple 4-bit design, but I'd like to do a 12-bit
computer (since my "inspiration" is a PDP-8).
The PDP-8/S is a -8 done in a bit-serial implementation. 78 microseconds
for some instructions!
If you don't mind making about a 15-year advance in the electronics
you'll be using, you might also seriously consider making a CPU via the
state machine route, using an EPROM and some counters. All math and logic
operations can very easily be done via table look-up in the EPROM. This
is a rather common assignment in lower-level computer engineering courses,
as it's something that can be easily wire-wrapped in an afternoon or two,
and it is extremely easy to try new microcode revisions.
Do you recommend any texts that did a neat state machine computer with a EPROM?
This sounds like fun, but would like to see some examples of what people
actually did first to help start a design.
-Dave
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology Voice: 301-767-5917
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