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PC Floppy Copy Protection: Formaster Copy-Lock
Preface This is Part 1 of a series of articles investigating various PC floppy protections, as I get them working in MartyPC . It assumes yo...
One of the customers of Formaster was none other than Sierra On-Line, and Copy-Lock was present on their seminal title King's Quest in its release as a booter for the IBM PC (A 'booter' is a game disk that did not require DOS, but was inserted directly at system startup). The read operation will complete, but status flags are set in the FDC result code bytes to indicate the bad CRC condition. As CPUs got faster, the time spent to execute a full 65536 iterations of LOOP decreased, with the effect that timeout windows implemented such as this started to shrink.
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