HP 65 Card writer compatibility testing

[John Garza (3665)]

Well... you CAN spread malicious code.
But its easy to erase by switching OFF.

All the 65s should be compatible as they came with prerecorded cards and multiple 'Pacs' available that can be read by any machine. If the machine wrote to a different standard, the card it created would not be readable by the same reader that reads the prerecorded cards.

The mechanism is self-clocking within limits. Some minor variation can be handled.
Not a surprise to me they still work. HP had good MEs as well as EEs !

The TI machines... well, that's another story. I have had TI-59s that could not share cards. Usually just tweaking the card speed pot fixes that.

For the proposed experiment - what would be a statistically significant sample size? How many working HP-65s are still around? Are the hypothesized failures normally distributed (as in new products) or perhaps some other more obscure curve due to aging components and mechanical wear?

I did something similar last winter. I wrote a simple wind chill program and wrote/read it across all six of my working HP-65s. They all worked perfectly.

-J