11 Apr
2007
11 Apr
'07
7:49 a.m.
On Wed, 11 Apr 2007, Alexandre Souza wrote:
There are NO possibilities that memory can be
piggybacked this way. When
you piggyback two memory chips, at least ONE of the pins must be routed
separately. At least this is what logic tells me.
I never seen a 128K *D*ram chip. SRAM exists. This is something that is
driving me crazy here, I cannot find any datasheets/pinouts on this part
number, nor any kind of info. Crazy.
For a *short* time, it was possible to get DRAMs in which half of the
chip was bad. I don't recall the size involved; it may well have been
256K DRAMs in which half of the chip was bad, resulting in 128K DRAMs.
These chips were configured to respond to half of the address space. You
could get them for either the high or low half.
They were specifically intended to be stacked as a pair to make a full
size memory bank. I have seen one machine that had such stacks in it.
This didn't last long, because the DRAM makers were eventually able to
figure out how to make enough good chips.
I have no documentation for this other than my own dodgy memory. This
was all many years ago. Early '80s, I think.
--
roger ivie
rivie at ridgenet.net