.setcpu "6502"
        lda     $1B00
        sta     $1B01
        rts
        lda     $1B00
        sta     $1B02
        lda     #$00
        sta     $1B03
        rts
        lda     $1B04
        clc
        adc     $1B06
        sta     $1B08
        lda     $1B05
        adc     $1B07
        sta     $1B09
        rts
        lda     $1B0A
        sec
        sbc     $1B0C
        sta     $1B0E
        lda     $1B0B
        sbc     $1B0D
        sta     $1B0F
        rts
        lda     #$00
        sta     $1B12
        lda     $1B10
        cmp     $1B11
        bne     L0050
        lda     $1B12
        ora     #$01
        sta     $1B12
L0050:  lda     $1B10
        cmp     $1B11
        beq     L0060
        lda     $1B12
        ora     #$02
        sta     $1B12
L0060:  lda     $1B10
        cmp     $1B11
        bcs     L0070
        lda     $1B12
        ora     #$04
        sta     $1B12
L0070:  lda     $1B10
        cmp     $1B11
        beq     L007C
        bcc     L007C
        bcs     L0084
L007C:  lda     $1B12
        ora     #$08
        sta     $1B12
L0084:  lda     $1B10
        cmp     $1B11
        beq     L0096
        bcc     L0096
        lda     $1B12
        ora     #$10
        sta     $1B12
L0096:  lda     $1B10
        cmp     $1B11
        bcc     L00A6
        lda     $1B12
        ora     #$20
        sta     $1B12
L00A6:  rts
        lda     #$00
        sta     $1B14
        lda     $1B10
        beq     L00C1
        lda     #$01
        sta     $1B14
        lda     $1B11
        beq     L00C1
        lda     #$01
        sta     $1B13
        rts
L00C1:  lda     #$00
        sta     $1B13
        rts
        lda     #$00
        sta     $1B14
        lda     $1B10
        bne     L00E1
        lda     #$01
        sta     $1B14
        lda     $1B11
        bne     L00E1
        lda     #$00
        sta     $1B13
        rts
L00E1:  lda     #$01
        sta     $1B13
        rts