HP-65 goes on hold after reading a card

[albertofenini]

Hi Tony, Hi Everyone
we swapped the ROMs, all of them but nada ...
We put the spare ROMs in the unit with the C segments always on but it still behaves like that
At this point we took the ROMS taken out from that unit and we put them in the unit the goes on hold, but it still does it ...
I would say both types of problem do not depend from ROMs ...
Would can we try if anything ?
take care !!!

(11-30-2020 12:01 PM)teenix Wrote:  

(11-30-2020 11:20 AM)albertofenini Wrote:  What do you mean with 1 command or 11 commands or 8 commands ?
Do they contain specific instructions that are loaded at the power up ?
Thanks !
Take care !

Whereas the HP-67 does code handling of the program which is stored in memory, the HP-65 does it through instructions that interface to the program buffer which is a separate chip not related to other memory storage.

These are the program buffer access commands and what hexadecimal ROM address they appear in.

pointer advance - Advance the program pointer by one
1EA 47B 49B 49D 930 9F4

mark and search - subroutine handling
444 488 4FC

search for label - Looks for a label like LBL A
4A8 4AC 4AF 4C2 9A7 A09

memory insert - insert a program step at the current pointer position
4E2 A1F

memory initialize - clear the program memory
936 A3C

memory full -> a - determines if program buffer is full
B6B

Memory Delete - delete a program step
091 460 462 4B4

In your case, maybe the [Memory Full -> A] instruction is not working properly. There is only one of these codes in ROM 3 (probably 1818-0075) Through a bunch of other instructions, this is what eventually lights the G segment when the buffer is full.

It may not be the instruction however, as the program buffer and or its logic might be faulty. Hard to tell.

cheers

Tony