Weird RAM

From: Eric Smith <eric_at_brouhaha.com>
Date: Sat Jun 22 02:40:16 2002

> But the weirdness...two DRAMs on a package is pretty weird (I suppose
> making a 32Kx 1 or 16K x 2), but these things have Apple logos.
>
> Huh?

Apple used those in the Apple ///. The 128K RAM card had three rows
of sixteen RAM chips. Even though it used an 8-bit processor (6502),
they did 16-bit memory accesses for video. To get 128K, two rows used
normal 16K DRAMs, and one row used the hybrid 32K parts. IIRC, the
data in and data out lines are tied together, the chips are effectively
32Kx1, with separate RAS# and CAS# strobes for the two chips.

Perhaps Fabritek happened to design a memory board for the same parts,
and someone upgraded the machine using chips salvaged from an Apple ///.

There was another form of double DRAM packaging, in which two DIP-packaged
parts are stacked. The leads of the top part are bonded to those of the
bottom part; I'm not sure how but it didn't look like a solder joint.
Note that the top and bottom parts are actually bonded out differently -
they are not interchangeable with each other nor with standard DIP DRAMs.
These were seen in some XT-class PCs.
Received on Sat Jun 22 2002 - 02:40:16 BST