HP-67 stuck in scientific (DSP 0) mode

[mbielman]

Tribidouille,

I had (still have) an old 67 that did (does) the EXACT SAME THING! Turns out there is a bad RAM location (I forget the actual address) that causes this. I believe it's in ROM4 (1818-0232) which is not all that helpful w/o a donor board.

Interestingly, at least in my case, if I leave it ON for a while while in this state (1/2 hour or so) it corrects itself and works OK except that one of the RAM locations remains bad which shows itself as PGM steps which you cannot change.

I had (have) another 67 that was so bad it would not display anything. Replaced the board in that one with the CPU board from Teenix. Works great!

regards,
Mark