30 Apr
2012
30 Apr
'12
6:19 p.m.
CRC wrote:
and also failed until he looked at the schematics for
his unit and
found yet another pin out for what appeared to be a 2716 equivalent.
The PROMs in question are NEC2316 about which information is unobtainium.
I think you're referring to the NEC ?PD2316E, which isn't a PROM. It's a
masked ROM. NEC's masked ROM business came from their acquisition of
Electronic Arrays, and the NEC ?PD2316E was originally the EA8316E, so
you can find data in either an EA databook, or an early NEC databook,
such as the 1982 NEC Catalog.
The 2716 pinout was designed to be similar to the pinout of 2K*8 masked
ROMs, but is generally not identical, because the masked ROMs had three
chip selects with mask-selectable polarities, while the 2716 has a
single chip select and a single output enable (which may in some
situations be used as a second chip select), and the chip select and
output enable are active low only, not configurable.
For example the 8316E/2316E (from any of several vendors) is used in the
Apple II and II+, but can't be directly replaced with an EPROM.
I've put a scan of the 1982 NEC catalog pages at:
http://www.brouhaha.com/~eric/vendor/nec/upd2316e.pdf
Eric