16 Feb
2016
16 Feb
'16
11:06 a.m.
On 2016-Feb-15, at 11:25 PM, Eric Smith wrote:
On Mon, Feb 15, 2016 at 11:31 PM, John Robertson
<jrr at flippers.com> wrote:
Apparently there actually is an equivalent EPROM, according to this
datasheet for the MM4203/MM5203 EPROM:
http://www.datasheetarchive.com/dl/Scans-006/Scans-00137265.pdf
It states they are pin-compatible to the MM5213/MM5231 mask ROMs.
The EPROM even has the selectable configuration mentioned by Rick.
(This is the only mention I've found of the 5231, I haven't come across this Nat
Semi ROM series before.)
Similar pinout to the 1702 (quite different than the industry standard of the
2708,2716,2732,etc.)
I expect they're too early and too uncommon to be covered by anything other than a
specifically-targeted programmer from the period.
It shouldn't be difficult to read them either way - adapter for an EPROM reader or
microcontroller, with additional power supplies as necessary, might have to consider
power-sequencing issues though.
Rick, what calculator are they in?, I'd be interested in looking it up on your site.
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.