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irq.src 566B

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  1. .page 'irq'
  2. ;
  3. ;
  4. ;
  5. sysirq pha ; save .a,.x,.y
  6. txa
  7. pha
  8. tya
  9. pha
  10. ;
  11. ;
  12. lda ifr1 ; test if atn
  13. and #2
  14. beq irq10 ; not atn
  15. ;
  16. jsr atnirq ; handle atn request
  17. ;
  18. ;
  19. irq10 lda ifr2 ; test if timer
  20. asl a
  21. bpl irq20 ; not timer
  22. ;
  23. jsr lcc ; goto controller
  24. ;
  25. irq20 pla ; restore .y,.x,.a
  26. tay
  27. pla
  28. tax
  29. pla
  30. rti
  31. ;
  32. ;
  33. ;
  34. ;.end