$EA31/59953:   Main IRQ Entry Point

EA31: 20 EA FF  JSR $FFEA     ; Increment Real-Time Clock
EA34: A5 CC     LDA $CC       ; Flag: Cursor blink
EA36: D0 29     BNE $EA61
EA38: C6 CD     DEC $CD       ; Timer: Count down for Cursor blink toggle
EA3A: D0 25     BNE $EA61
EA3C: A9 14     LDA #$14
EA3E: 85 CD     STA $CD       ; Timer: Count down for Cursor blink toggle
EA40: A4 D3     LDY $D3       ; Cursor Column on current Line
EA42: 46 CF     LSR $CF       ; Flag: Cursor Status
EA44: AE 87 02  LDX $0287     ; Background Color under Cursor
EA47: B1 D1     LDA ($D1),Y   ; Pointer: Current Screen Line Address
EA49: B0 11     BCS $EA5C
EA4B: E6 CF     INC $CF       ; Flag: Cursor Status
EA4D: 85 CE     STA $CE       ; Character under Cursor while Cursor Inverted
EA4F: 20 24 EA  JSR $EA24     ; Syncronise Color Pointer
EA52: B1 F3     LDA ($F3),Y   ; Pointer: Current Color RAM Location
EA54: 8D 87 02  STA $0287     ; Background Color under Cursor
EA57: AE 86 02  LDX $0286     ; Current Character Color code
EA5A: A5 CE     LDA $CE       ; Character under Cursor while Cursor Inverted

Jump from $EA49:

EA5C: 49 80     EOR #$80
EA5E: 20 1C EA  JSR $EA1C     ; Print To Screen

Jump from $EA36, $EA3A:

EA61: A5 01     LDA $01       ; 6510 On-chip 8-bit Input/Output Register
EA63: 29 10     AND #$10
EA65: F0 0A     BEQ $EA71
EA67: A0 00     LDY #$00
EA69: 84 C0     STY $C0       ; Tape Motor Switch
EA6B: A5 01     LDA $01       ; 6510 On-chip 8-bit Input/Output Register
EA6D: 09 20     ORA #$20
EA6F: D0 08     BNE $EA79

Jump from $EA65:

EA71: A5 C0     LDA $C0       ; Tape Motor Switch
EA73: D0 06     BNE $EA7B
EA75: A5 01     LDA $01       ; 6510 On-chip 8-bit Input/Output Register
EA77: 29 1F     AND #$1F

Jump from $EA6F:

EA79: 85 01     STA $01       ; 6510 On-chip 8-bit Input/Output Register

Jump from $EA73:

EA7B: 20 87 EA  JSR $EA87     ; Scan Keyboard
EA7E: AD 0D DC  LDA $DC0D     ; CIA1: Interrupt (IRQ) Control Register

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Kernal-Reference:

 LDA $EA60   : $E3A8