NoV-64: Can't Access RAM Chip 3


I had a hang while attempting to READROM the contents of a ROM images file into the four HEPAX RAM pages on chip 3. Since, I have not been able to access the chip. Trying to set the h4100 control word to 003, 103, 203, things hang momentarily and the screen displays a sometimes blinking NONEXISTENT that only clears when I remove the battery.

I have tried wiping the ROM in microbrn, clearing the RAM with CLRAM4.hex (the calc returns CLR OK), and using the CRF procedure in an unsuccessful effort to access the bum chip and clear any corrupted hex code. No dice. Any effort to point the calc to that chip yields the disturbing behaviour noted above. I have also manual cleared the RAM on chips 0, 1, and 2, which, by the way, seem to be behaving fine.

Any ideas? Diego advises that it is darn near impossible to damage these things with bad programming, so I hope I can recover this.




Just bumping this.

The ominous lack of response after nearly 12 hours makes me fear that I have severely fried something.

I have written Diego directly, but I know he is vacationing and I was hoping someone else in the group could advise first.

Many hopeful thanks in advance,



I am heading out for a family night right now and will report details later, but I did recover the corrupted RAM and now have a fully functioning NoV-64 once again.

More later!



Hi Les,

This is a two side reply:

First I'm sorry not being on-line at first instace to help solving your chip #3 issue.

Second I'm happy to see you've got to fix it yourself... that's what the CRF was designed for... :-)

Hope you get a nice buch of fun out of your HP-41/NoV tools!

Cheers from Dominican Republic.


Edited: 28 May 2012, 10:07 p.m.


Thanks, Diego. I already told you in the email, but for the benefit of others, here is what I did:

I used HEXEDIT to change h'4100 contents to h'003. Within a second--I didn't even have to leave HEXEDIT--NONEXISTENT started flashing. I did NOT remove the battery this time--instead, I executed the ENTER-double ON manoeuvre and found myself with a normal display. I did NOT turn off the calculator--I simply executed CLRAM for 11 down to 8, and, voilà, on turning the calc on and off I am able to point myself to RAM chip 3 by changing h'4100 to any of the configurations that do so.

Of course, I lost everything, such as it was, in the 4 pages of HEPAX RAM in chip 3, but considering that I believed I had physically damaged the memory, this is a small inconvenience. I have been able to restore my desired ROMs and other files using ClonixConfig and mass storage routines with HP-IL and PIL-Box.

Thanks for the reply. I am learning a lot and sorting out things on my own.


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