Copy protection schemes on the PET

From: Marko Mäkelä (
Date: 2000-09-26 08:25:23

Yesterday I acquired a CBM 8050 dual disk drive unit and a piece of
software ("Valmisbetoni", a Finnish program for optimizing concrete
mixtures) that should be transferred to a PET emulator (i.e. VICE). Good
news: the IEEE-488 interface of my PET works.  Now I only have to transfer
the stuff over, probably using prlink.

The dongle protection seems quite simple.  It appears that the software is
written in BASIC and then compiled.  The dongle plugs to the cassette
port (either of them), and the program checks for the dongle right in the
beginning.  If it doesn't find the dongle, it'll jump to the reset
routine.  I think that it should be easy to remove this protection using
the machine language monitor of VICE.

This brings a question to my mind.  What kinds of copy protection were
used on the PET?  Were ROM chips and cassette port dongles the only ways,
or were disk errors used as well?


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