# Pastebin LQ5rbg7N
init:
    lda #$F1
    sta $E420

    ; CB1 only visible;
    lda #$08
    sta $E01A

    ; Put interrupt registers and such.
    lda #>irq
    sta $FFFF
    lda #<irq
    sta $FFFE

    lda #>nmi
    sta $FFFD
    lda #<irq
    sta $FFFC

    ; Return
    rts