Hey! That must be the same UART board I have lying about somewhere. It has
a bunch of shift registers in to-5 cans (to save space) and calculates
parity using a JK flipflop.
This thread seems to have started with the notion of even building the
flipflops from discrete transistors and passives. That 4x5-inch board would
grow to the size of a closet door using that thechnology. What's more, the
power would have to be distributed with #16 wire.
Dick
-----Original Message-----
From: CLASSICCMP_at_trailing-edge.com <CLASSICCMP_at_trailing-edge.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Wednesday, October 20, 1999 9:46 AM
Subject: Re: OT: how big would it be?
>>I have trouble with the notion of the uart filling a 9 x 11 board given
>>that I'm holding one that's occupying 4 x 5 inches in SSI. Yeah, the shift
>>registers would take a bunch of space but I don't see it using anywhere
>>near the amount of real estate suggested.
>
>I'd suggest a electromechanical (or optomechanical) UART instead. You
>know, like in a Teletype :-).
>
>>> A pdp-8 (early) had a pannel roughly 24"x50" with flip chip modules
mostly
>>> transistors and the 4k core was a 10" tall rack section. for rough
>>> comparison. In many respects the 8080 is a far more complex CPU and
would
>>> be significantly bigger. It would also be slow compared to the NMOS
part.
>
>>I suspect you could build a pdp-8 using contemporary layout tools and
discrete
>>technology that, excluding the core stack, was an order of magnitude
smaller.
>
>And repackaging would also save a lot of money: a large part of the cost
>of a Straight-8 is all those gold plated fingers and edge connectors, and
>the backplane wiring. Get rid of that - so that your CPU resides on
>a single (even if large) PC board - and you're way ahead. (Well, way
>ahead if everyone else is still in 1965...)
>
>>> Doing it in ttl or bit slices would still be big, I've done that. using
>>> 2900 parts(ca mid to late '70s) the CPU equivelent was over 100 chips
and
>>> filled 4 10x8" cards.
>
>>That sounds about right; I recall building a PDP-11 clone using 2901/2910
parts
>>as part of an undergraduate CPU architecture course in the same era and
using
>>about the same number of parts.
>
>Of course it's also possible to do it on a single card using SSI and
>MSI TTL, maybe with a few bipolar PROM's. Take a look at the 11/04 CPU or
>the original Nova, for example.
>
>I recall - back in the mid-70's - that Radio Shack sold transistor-based
>logic module kits (PC boards) that could be strung together to make
>things like binary counters, etc. Does anyone else here remember these?
>Or, even better, still have the modules around?
>
>--
> Tim Shoppa Email: shoppa_at_trailing-edge.com
> Trailing Edge Technology WWW: http://www.trailing-edge.com/
> 7328 Bradley Blvd Voice: 301-767-5917
> Bethesda, MD, USA 20817 Fax: 301-767-5927
Received on Wed Oct 20 1999 - 11:23:15 BST