HP71b modules - what are they ?


I have two HP71b ROM modules labelled "CMT71-64E". Can anyone tell me what these might be ?, and are they useful to anyone ?, and can ROM modules be converted in to RAM modules by replacing the chip inside ??? Thanks - John



I don't think you can replace ROM by RAM there,
because ROM is read-only, whereas RAM is read-and-write.
So there may be an other circuit layout.

Nevertheless there were 64K RAM modules for the card reader port of the HP-71.




This is an EPROM device.

They also made 64K RAMs for the front plug-in ports.


I'd bet these are aftermarket modules made by Corvallis Micro Technology due to CMT prefix..

I'd guess "CMT71-64E" is a 64k*bit* (meaning 8k byte) RAM module just because I remember them making 71B stuff, and I don't recall them making any 71B ROMs.

-Bill Wiese
-San Mateo, CA


I suspect that if you look at the ROM, you will see the UV window on the device.

The 64E is a UV erasable EPROM.


You're right, there is a window on them. So I guess they're 64K UV EPROMS from Corvalis Micro Technologies. So the contents are presumable useless (to me at least). So, any ideas on how you program the little suckers ??. Can another ROM be copied into them etc ??? Thanks - John

Possibly Related Threads...
Thread Author Replies Views Last Post
  HP Prime - Short "learning" modules CR Haeger 1 414 11-27-2013, 02:13 PM
Last Post: Jonathan Cameron
  Library#4 Modules mass-update and New Overlays Ángel Martin 0 428 11-09-2013, 05:55 AM
Last Post: 'Angel Martin
  hp41cv memory modules tim peterson 10 1,112 11-07-2013, 11:09 PM
Last Post: Garth Wilson
  HP71B Spy Radio Crypto Donald Ingram 2 510 10-14-2013, 10:51 AM
Last Post: Eric Smith
  Best way to test HP-71B RAM modules (the 32K/96K ones etc.)? Philippe Lasnier 4 827 09-25-2013, 09:54 AM
Last Post: Philippe Lasnier
  HP-41 New versions of your favorite modules - with an AOS twist :-) Ángel Martin 13 1,273 06-21-2013, 01:29 PM
Last Post: Diego Diaz
  HP71B to HP 41 Translator ROM Manual Michael Lopez 5 653 04-25-2013, 03:51 AM
Last Post: Mike (Stgt)
  Rather large missed opportunity - a pile of HP71B's Chris Smith 3 504 04-19-2013, 07:30 AM
Last Post: Chris Smith
  Has anyone else had problems with ebay member 'hp71b'? Dan Grelinger 6 733 01-26-2013, 09:33 AM
Last Post: aurelio
  Programming CMT EPROM modules for HP-41 Paul Berger (Canada) 4 651 01-22-2013, 06:04 PM
Last Post: Paul Berger (Canada)

Forum Jump: