15 Feb
2016
15 Feb
'16
11:25 p.m.
On Mon, Feb 15, 2016 at 11:31 PM, John Robertson <jrr at flippers.com> wrote:
Rick, if you want to archive these PROMs (highly
recommended) you should be
able to find a Data I/O 29B and get one of the programming packs that
supports NS chips. I may have such a combination in my collection, but that
PROM is not listed in my DATA I/O library of readable parts.
They're not PROMs, they are masked ROMs, and there is *NO* equivalent
PROM, so it's unlikely that there's any support for reading them on
any PROM programmer.
Part of the
problem with the early PROMs is they needed a Sync or Clock signal to be
able to be read.
The MM4221/5221 is fully static, so it doesn't have that particular problem.
It's PMOS, and needs +5V and -12V supplies. The outputs are
TTL-compatible, but the inputs technically are not, due to Vih min of
3.0V. Could be driven by TTL with a pullup resistor, or by CMOS.