21 Nov
1998
21 Nov
'98
8:03 p.m.
On Mon, 16 Nov 1998, Pete Turnbull wrote:
Ugh! Obviously my information source was incorrect, or he was talking
about the chips in a vaguer sense than I though.
Ack! I need a
bunch of these to get a PET 2001 going (all of the 6550s
are bad, and I was told that the 2114 is the same part?) and a VIC 3K RAM
Expander fixed.
They're NOT the same. I can't find a pinout, but they're a different
(physical) size and ISTR they use different voltages as well. MPS6550s will be very hard to find as they were never
second-sourced by
anyone, as far as I know.
So even memory becomes a 'custom chip' from Commodore. :)
They're 22-pin (0.4" wide instead of
0.3") 4096-bit (1024 x
4) SRAMs. 2114's are 18-pin 4096-bit (1024 x 4) SRAMs.
If I had some extra 2114s sitting around, I would have known this by now.
I see they are both 1024 x 4 SRAMs, so maybe something can be done to get
them to work.
Even MOS Technology didn't make them for very
long, which is why only the
earliest PETs used them.
I only have two PETs, and both of them use 6550s. (Both of them also have
the nice 9-inch _white_ display, too.)
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
--
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/