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   comp.sys.apple2      Discussion about Apple II micros      56,720 messages   

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   Message 55,188 of 56,720   
   Steve Nickolas to All   
   Re: ProDOS boot block?   
   28 Dec 21 03:11:55   
   
   From: usotsuki@buric.co   
      
   Currently the most efficient x86-side code I can come up with is this:   
      
   B8 01 02 B9 02 00 30 F6 31 DB 8E C3 BB 00 7C 26   
   C7 06 FE 7B CD 13 EA 00 7C 00 00   
      
   That's pretty much the same code I described before, except that once the   
   registers are set I place an "int 13h" at 0000:7BFE and jump hard to it.   
   (This 8086 code could probably be done even more efficiently.)   
      
   Since I haven't yet RE'd the entire ProDOS bootloader - only as far as   
   $096C, and that only basically - I'm not really sure what code might be   
   safe to maneuver around without breaking things, other than the stuff that   
   I was able to identify as being part of the SOS chainloader.   
      
   Still, this seems to suggest that a 6502-8086 diglot bootloader is indeed   
   possible.  (It would only really be feasible on a 1.44 MB floppy though   
   which is quite rare on the Apple ][ line!)   
      
   -uso.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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