Restoring HP-65

[teenix]

(01-07-2019 09:59 PM)albertofenini Wrote:  Hi everyone,

after restoring the HP65 and its card reader, we have been able to read most of the pre-recorded cards, and record some new cards.
However, what surprises us, is that we are not able to successfully write the type of cards that should really belongs to the HP65.

Look at the attached picture, we have even been able to record on both sizes of a card, and I believe that some of the cards successfully recorded are from a HP67,
while we can't succeed in writing on the first type that was coming with the HP65 itself.

Has it happened to someone before ?
Any idea ?

Does this happens on all available HP65 cards, and all of your working HP65 calculators.

If just 1 calculator then maybe the CRC circuit is not quite right.

I'm not really sure but, I think the 65 and (67 and 97) have different CRC chips, so maybe different card RW requirements ???

(01-07-2019 09:59 PM)albertofenini Wrote:  One more question.
If we record a program on a card, says about 65 steps, and then we override this with a new recording for shorter program, says about 50 steps,
will the old program overridden or the 15 more steps will remain and is this goin to be a problem ?

take care Alberto

The CRC will write to the card what ever is in the program buffer. If the program was cleared before entering your new program then unused memory will be NOP's, else it will have what ever was there that didn't get overwritten by the new program.

cheers

Tony