HP 65 Card writer compatibility testing

[teenix]

(08-16-2023 06:31 PM)carolinahomes Wrote:  My hypothesis is that there are some machines that are not compatible with others. This is the only way I know which to properly test whether it's true or not.

After all these years, it's remarkable that this system still works at all.

There would have been speed variation factors considered originally, different calculators, temperature, humidity, phase of the moon etc. I would think, assuming the read and write functions are ok, then the only errors would be either a slow/fast running motor or the CPU board master timing is out of spec due to component aging etc. These errors may not impact a user that doesn't swap cards, and the errors may not even be known, but as you say, they may not work in another machine.

Assuming both cards work fine in their own 65's, I guess the question then is, if they don't in another 65 which one is at fault.

One good thing about swapping cards is that you cannot spread a calculator virus ;-)

cheers

Tony