The author of the MartyPC IBM PC emulator writes about vintage PC hardware, emulation accuracy, and floppy disk copy protection schemes.
HN commenters recommend the floppy copy protection series, especially the interview with Quaid Software's Robert McQuaid, and the hardware-validating emulator post.
Another great article from the same author that I found when browsing their blog after the previous article:
https://martypc.blogspot.com/2023/06/hardware-validating-emulator.html?m=1
Probably should be a separate HN submission at some point.
Yes, it was apparently very visible: https://martypc.blogspot.com/2024/09/pc-floppy-copy-protection-vault-prolok.html
But as I mentioned in a sibling comment, I’m not sure it was ever confirmed that it was really a laser that made that mark.
The accompanying interview with the founder of Quaid Software who defeated the Vault Prolok is also very interesting:
[0] https://martypc.blogspot.com/2024/09/pc-floppy-copy-protection-interview.html
Don't miss the interview with Robert McQuaid, a fascinating read:
https://martypc.blogspot.com/2024/09/pc-floppy-copy-protection-interview.html