> If that chip format has enough address lines for chips larger than
> 256Kx1 and these extra address lines are hooked up on the motherboard,
> one could then try to track down these chips, unsolder all 144 of
> the old ones, and solder in all 144 of the new ones. What fun! :-)

JEDEC x1 DRAMs have enough pins to go up to 4Mx1 without changing existing
pinouts.

Early 64Kx1 DRAMs required separate VBB and VPP (-2V and >5V supplies).
As capacity increased, these supplies were generated on-chip, so the pins
could be used for address lines.  Each fourfold increase in capacity
requires only one additional address line (since addresses are multiplexed
on RAS- and CAS-).

David Jones           micron hacker by day:              jones@mosaid.com
                      kernel hacker at night:            dej@achilles.net