Restoration: how far should it go??

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sun Jun 15 14:55:22 2003

> I see you have higher standards than IBM, for a while after the AT was
> released they sold ram that was two chips piggy backed so they could get more
> ram on the board.

Hmm.. The oriignal PC/AT motherboard did have piggybacked RAMs, but it
wasn't an IBM kludge. Those were special RAM chips (the pinouts were
strange, with pin 1 actually used for something and the CAS/ signal from
each chip brought out separately (I think it was CAS/)), and I don't
think they were soldered together (looks more like ultrasonic welding to
me). I'd assumed these were a 'standard' 128K RAM module, something like
a Mostek part I once saw (18 pin DIL) which was a ceramic module with 2
chips soldered on top.

Incidentally, I have seen piggybacked sockets in the catalogues. 16 pin
ones with all pins commomed except 4 and 15 (RAS/ and CAS/ for normal
DRAMs IIRC) and 28 pin ones with all pins commoned except 20 (CS/ for a
JEDEC SRAM or EPROM). Interesting idea...

-tony
Received on Sun Jun 15 2003 - 14:55:22 BST