From Olivier Goguel:
For Apple 2GS die-hard fans, Nucleus is finally available as a PRODOS 8 system application to be able to be run from a HDD : joie dans les chaumières!
It was quite challenging to dive into 65C18 code after all those years… to struggle against a 30-year-younger-me that had the funny idea to protect his code against this kind of hack!
CMP $03f3 // Check that RESET has not been altered
CMP #$6b18 // Check that control panel is not accessible
LDX $3425 // First Indirection
LDA $00,X // Second
LDA $21,X // Third => $987 (Boot sector!)
CMP #$0bd0 // Check instruction BNE +13
Hope those who can still decypher assembly will appreciate that!
For more info, check GitHub (https://github.com/ogoguel/nucleus-p8) or the story behind the letter received from Apple at that time (https://lnkd.in/dV5aQUP3)