unreadable HP cartridges

[Tim Shoppa]

> Digital information is stored on the tape using a delta distance
> encoding scheme.  The "1" distance is approximately 1.75 times
> longer than the "0" distance.  The magnetic polarity is
> irrelevant, only the distance is important.

This is very similar to the Apple II cassette modulation scheme.

Hmm.. Woz worked for HP at the time...

If you look at other early cassette tape "standards" they tend
to be more FSK-like than distance-encoding type.  e.b. Kansas
City Standard.

Tim.