3 May
2002
3 May
'02
1:30 p.m.
These days you can get a 32K*8 SRAM chip in a 28 pin
DIL package for very
little money. And they're easy to find. There's little wiring up to do
(wiring up rows of wire-wrap sockets pin-for-pin is not my idea of fun...)
One of those, and a suitable EPROM would be enough memory for most small
homebrew 8 bit systems. 32K RAM + 32K EPROM is a full memory map. If you
need more RAM and less EPROM, use 2 of the 32K*8 RAM chips and just
disable them for the part of the memory map where you want to put the
EPROM. It's easier to do that than to mess about with several smaller
RAMs IMHO.
-tony
Agreed, KISS is the idea and these 32K srams are very reliable and
plentiful.
Dig into discards or osolate mid to late 486 and early pentium
boards, these boards used 32K or 64K x 8 bit DIPs in sockets.
Ditto to EPROM's in ceramic package w/ quartz windows from those.
Usually 64K x 8 or 128K. Better yet, flash chip. Still can be hot
swap flashed on "disposeable" late model 486 or mid period pentium
boards w/ your own file and bios flash program that doesn't care
what file it is of your own creation and use flash IC on your
homebrew 'puter instead of eprom as an "eprom". This beats having
eprom programmer. :-)
These common flash chips (DIP package) is 32pin and are usually 128K
or 256K x 8.
I dug up many boards this way for free or for a price of a decent
meal.
Cheers,
Wizard