Re: Replacing SRAM with a SIMM
- From: et472@xxxxxxxxxxxxxxxxxxx (Michael Black)
- Date: 3 Sep 2006 15:40:56 GMT
(cbarn24050@xxxxxxx) writes:
FyberOptic wrote:Well kids today don't know how lucky they are. I recall paying at least
The thing is though, roughly 32k of system memory obviously isn't very
much space to work with. I'd like to be able to implement the same
style of bank-switching into this extra system ram, adding maybe up to
512k-1mb of switchable storage capability, to avoid much disk activity.
But the problem is sram isn't cheap, especially when you start getting
into such "large" capacities.
Sram is cheap! 512kbx8 chip is around $10.
$40 for 4K of static ram in the fall of 1981 to bring my OSI Superboard
up to 8K of RAM.
Back then, dynamic was the only way to get larger amounts of memory
in a small space and for the least amount of money, but of course
it had it's faults, like the requirement for extra circuitry.
The RAM caught up with the 64K address limit of the 8bit CPUs towards (or
shortly after) the time when the move to 16bit CPUs started coming into
use.
As people have pointed out in the past, cache ram off older "IBM Compatible"
computer motherboards is static and 8bit wide and will supply lots
of RAM for nothing when you find those boards in the garbage.
I think the poster needs to rethink his plan. As you point out later,
if you start loading something down with large amounts of memory, one
might as well switch to a CPU that can address it directly, rather than
bank switching, which was always rather lame. Bank switching back then
tended to be for data, not programs, since it was problematic to plan
for more code being in the right place at the right time.
He likely could consider a disk drive type solution, only using
a compactflash card or the like as the drive, connecting it as I/O
rather than address space, and just have a simple load in the monitor
ROM.
Michael
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