OT: how big would it be?

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Wed Oct 20 10:56:34 1999

> Using discrete transistors to build flop cells on that scale would be so
> large that getting the timing to work would be a real pain. Core wouldn't be
> bad at all; mid 70's core technology stuffed 32K * 20 in an 8" x 4"
> area with no sweat; drivers and transceivers wouldn't double that.

Ok now delete all teh integrate circuits like the sense amps and substitue
a flipchip sized module for each read amp (note some of those chips were
duals and quads). Then look at the packages of diodes and use individual
diodes.

> 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.

Try a TTY PDP-8 omibus card. Keeping in mind yes the uart part of that
is only part of the card it still has tobe interfaced. The ttl only
version is a full quad card. Again as transistors it will grow.

Having had my head in the RCSRI PDP-12 and LINC-8 plus the PB-250 I have a
better idea of real machines using nothing but transistor technology.

Granted modern parts could really improve the packing density.

> multilayer boards while our '60s compatriots were laying stuff out by hand
> on light tables (been there, done that, never again).

Yes, touch way to go.

> 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.
> Using '70s core technology you could get the stack somewhat smaller while
> increasing the storage density by a factor of eight. The 8080 would without
> a doubt be larger than the '8 and slower than the NMOS version of the chip;
> it would also cost a fortune to build.

Maybe. If you cheat and use 70s core tech (ICs) that's a big savings as
the core planes were never the total system anyway. It's the
drivers/decoders that grow huge!

Also you'll never get the power/cooling of a say straight-8 even if size
reduced to come down near as fast and the ultimate problem may be cooling
or deliver the AMPs of power.


Allison
Received on Wed Oct 20 1999 - 10:56:34 BST