Tag Archives: Commodore 1541

Vorpal disks: perhaps the most reliable way to set write splice offsets

Posted on December 17, 2020 by Luigi Di Fraia

By now my readers should be familiar with the fact that one of the most severe risks involved in writing the data of a protected disk image back to a floppy disk consists in starting (and ending) the write operation … Continue reading →

Posted in Retrocomputing, Reverse Engineering, Technical | Tagged , , , , , | 4 Comments

Flux Studio: all Vorpal blocks can now be decoded

Posted on December 16, 2020 by Luigi Di Fraia

I finally also finished implementing the decoder for custom Vorpal blocks on track 18. There are four of these in California Games, used to load the main drive code into the drive RAM. Here’s the debug output from both Vorpal … Continue reading →

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Flux Studio: progressing with the development while dissecting Vorpal

Posted on December 14, 2020 by Luigi Di Fraia

My current efforts with Flux Studio when it comes to Vorpal are twofold: create a data decoder in order to check the integrity of G64 images (similarly to what TAPClean does for TAP images) detect at which point in a … Continue reading →

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Dissecting the Vorpal (later) disk protection – part 1

Posted on December 10, 2020 by Luigi Di Fraia

Update to this post: California Games does NOT load the main drive code from track 17.5 or 18.5 as previously stated. It loads from track 18.0 as the stepping instructions detailed below just step outward and then back onto track … Continue reading →

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How the block-sync and byte-sync signals of a Commodore 1541 drive work

Posted on December 9, 2020 by Luigi Di Fraia

If, like myself, you decide to delve into the mythical world of disk copy protections for the Commodore 1541 drive, you might find out that useful reference documentation is a tad scattered all over the place. In fact, I haven’t … Continue reading →

Posted in Retrocomputing, Reverse Engineering, Technical | Tagged , , , , | 8 Comments