9 Jan
2009
9 Jan
'09
4:33 p.m.
On Jan 9, 2009, at 5:59 PM, Ethan Dicks wrote:
Hence, they're not "weird chips". =) It's the weird ones I'm
worried
about.
OK. I think we are on the same side here ;-)
We usually are. :)
JEDEC ones - I don't have the time to untangle wierd ones.
Yeah. The weird SRAMs that the SBC6120 uses are PC cache chips
too, aren't they? They've become pretty tough to find in recent
years. I really like that they're four bits wide, though, for that
application.
Thanks, I think so too. And it'll weigh a few pounds! :)
Standard
chips good. Weird chips from the PC world, bad.
I'm not advocating the reuse of SMT 128K cache chips, but the 32Kx8
DIP chips from old motherboards have a JEDEC-compatible pinout... The DIP cache SRAMs are no longer cheap-as-chips, but
some of us
have
a tube or two stashed away and I sure don't mind using them for
non-battery-powered circuits.
The JEDEC ones, or the "weird" ones? I see some
from time to time, and I
grab them if they're "standard" enough. I got a pair of really
20ns nice
cache SRAMs on eBay last year, Paradigm PDM41256SAs. Despite their
seemingly familiar part number, they are 32kx8 SRAMs, not 256kx1
DRAMs.
They're in 0.3" ceramic 24-pin DIPs. I'm saving them for a
"pretty" Z80
SBC that I'll be building soon, on which all chips are ceramic.
(I've
always had a great love for ceramic chip packages, and I grab useful
ceramic-packed chips whenever I can)
Nice. Sounds like it'll have great presentation value. You have purple ceramic for the VLSI or just grey?
I've got the Z80 CPU, CTC, SIO, and PIO chips in purple/gold.
I've got some purple/gold SRAMs, but not quite enough for this
project. Chuck has some medium-density purple/gold 16Kbx1 SRAMs that
I'm thinking about trying to talk him out of. If I don't go that
route, I'll probably use those Paradigm gray ceramic SRAMs. I'll do
the address decoding and other sundry stuff in a ceramic UV-erasable
PAL22V10, of which I have a few tubes.
I also have some HP intelligent hex displays, along the lines of
the TIL-311, I'm sure you've seen them. Most of them are
encapsulated in red injection-molded plastic, but I have a handful of
fairly rare 5082-7359s, which are hermetically-sealed purple ceramic
with a glass cover. They are absolutely gorgeous.
I'll probably put the board between two 0.25" pieces of lucite.
-Dave
--
Dave McGuire
Port Charlotte, FL