Nucleus Now Available as ProDOS 8 App

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!

LDA $03f4
EOR #$a5
CMP $03f3 // Check that RESET has not been altered
BEQ InfiniteLoop1 
REP #$30
LDA $e10048
CMP #$6b18 // Check that control panel is not accessible
BNE InfiniteLoop2

LDX $3425 // First Indirection
LDA $00,X // Second
LDA $21,X // Third => $987 (Boot sector!)
CMP #$0bd0 // Check instruction BNE +13  
; KO!

Hope those who can still decypher assembly will appreciate that!

For more info, check GitHub ( or the story behind the letter received from Apple at that time (

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