On Oct 19, 18:10, Ian Primus wrote:
I have a very large pile of 27cx321
chips, made by a company called ICT, but I have been unable to
program
them, since my programmer doesn't have the codes
for them in the
manual, and they don't work at the normal 2732 setting.
No, they don't, and if you try it, you may destroy them. They're
high-speed (usually 35ns, but the suffix -35, -40, or -45 gives the
actual number) 4k x 8 UV-erasable EPROMs, and to get the speed they use
a different cell construction and a different programming technique.
The bits in an erased device are "undefined" and whether you want a
'1' or a '0' you have to program the actual value. Pinout is pretty
much the same as a 2732 except that pin 20 is /CS1 instead of /OE, and
pin 18 is CS2 (active high) instead of /CE.
My ICT data book doesn't give the programming algorithm, which is
obviously proprietary. It just says contact ICT or use a DATA I/O
Model 29B with Unipak 2 or 2B firmware version V15.
Oh, and like every other EPROM manufacturer I know, ICT say that
exposing it to UV for longer than necessary will affect reliability,
shorten the life, or in extreme cases, destroy the device, so don't
expose them to a UV eraser (standard 12mW/sq.cm) for more than 20
minutes. Overnight is a bad idea!
--
Pete Peter Turnbull
Network Manager
University of York