Making new HP-65/TI 59 magnetic cards out of VHS tape

[Dave Frederickson]

(11-04-2021 12:33 PM)KimH Wrote:  I am not 100% sure how the 65/67 works, but I do know that the cards for the 75C & 71B has a SYNC/TIMING track which is written in the production.

The 71/75 cards are hand-pulled - not a very precise speed, so a timing track is required. All other HP card readers use a speed-controlled motor, so a timing track isn't necessary.

As a side note, mag cards can be degaussed to wipe any stray magnetic data. This, however, should NOT be done to the hand-pulled cards as it will destroy the timing track.