Disabling HP65/67 card reader write protect

[Thomas Okken]

(03-08-2019 02:01 AM)rprosperi Wrote:  Try cleaning the card with a pen eraser (Staedtler Mars, etc.). Sometimes this will clean the oxidation that has built up on the magnetic side of the cards; be careful how you hold the card down while rubbing, it is easy to bend a card. But sometimes, these cards can be too worn or affected by strong enough magnetic fields that they can't be restored to working order again.

Good idea! It's been so long since my HP-41 days, I'd completely forgotten about the eraser trick. I should have a couple of Staedtler Mars erasers lying around somewhere.

(03-08-2019 02:01 AM)rprosperi Wrote:  Send me your address via PM, I'll mail you some cards.

Thank you! But before I take you up on that, I'm going to try some more tests with the card I have mutilated already. I got a pack of AAA lithiums since the alkalines I was using weren't holding up too well under the constant card reader usage -- with these new batteries I should be able to do a nice methodical series of tests without further interruptions. I'll post again tomorrow with my results.