NMI:
           PHA
           TXA
           PHA
           TYA
           PHA

           LDA #$20
           STA $2006
           LDA #$20
           STA $2006       ;Point to Name Table

           LDA SNG_CTR
           LSR
           LSR
           LSR
           LSR
           ORA #$80        ;Point to right chr.
           STA $2007
           LDA SNG_CTR
           AND #$0F
           ORA #$80
           STA $2007

           LDA #$00
           STA $2006
           STA $2006
           STA $2005
           STA $2005

           LDA INT_EN
           BEQ NO_INTS
           JSR PLAY_ADD    ;play tune

NO_INTS:
           PLA
           TAY
           PLA
           TAX
           PLA
           RTI