Floppy Disk Preservation Project
Vorpal - Early
Contributed by Dr. Markus Brenner

This protection is seen on many high-profile releases by Epyx from 1985-1987. Summer Games II, Winter Games, World Games, Rescue on Fractalus, Barbie, G.I. Joe, Hot Wheels, etc.
The protection was written by Scott Nelson.

The copy protection is checked on track 20. Starting from sector 1, the number of bytes between Syncs are counted for the next 17 blocks. Also, the first byte triggering the sync is read (in other terms, the last byte until the sync signal is registered). If any of these values don't match the expected values, the copy protection failed.

lengthlast byte b4 sync
Header sector 1$11$af
Data sector 1:$4d$ff
Header sector 2:$11$af
Data sector 2:$4d$ff

Apple ][ Registry Stats
Total Registered: 152

Top 5 Earliest Serials
Neil Thayer: -3929
Unknown: A2S1-0001
Jef Raskin: A2S1-0002
Bob Bishop: A2S1-0013
Achim BaquƩ: A2S1-0025

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C64 Registry Stats
Total Registered: 3419

Top 5 Earliest Serials
Unknown: 0019
Charles Lynch: 0021
David Bradley: s00001044
Jeremy DuBois: S00001185
John Justice: s00001281

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Disk Database Stats
Titles archived: 3551
Titles verified: 1376

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All content copyright (c) 1971- by Peter Rittwage. All programs mentioned are copyrighted by their respective owners.