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1. • 1: CommentAuthorThomas Cherryhomes
   • CommentTime28 Feb 2021 zmieniony

    
   I am needing to consistently poll time in BASIC for a patched version of FoReM-26M BBS I am releasing. However, when I try to execute the following inside a USR ADR string, it crashes, why?
   
   ```
   PLA           ; needed for USR
   LDA $D301
   PHA
   AND #$FE
   STA $D301
   JSR $FFC0
   PLA
   STA $D301
   RTS
   ```
   
   -Thom
2. • 2: CommentAuthormono
   • CommentTime28 Feb 2021

    
   It should be:
   

   AND #$FE

   
   instead of
   

   AND $FE
3. • 3: CommentAuthorThomas Cherryhomes
   • CommentTime28 Feb 2021

    
   yeah, that was a typo, still crashes for some reason.
   
   the machine code winds up being
   
   68 AD 01 D3 48 29 FE 8D 01 D3 20 C0 FF 68 8D 01 D3 60
   
   which I convert to decimal and then read out using a small stub to create the X=USR(ADR("")) string...
4. • 4:
      
     CommentAuthorKrótki
   • CommentTime1 Mar 2021

    
   I guess it crashes because you are disabling the OS without disabling IRQs and NMIs.