|0000
    @counter $1
    @position $2

|0100
    ( set up treble )
    #0300   #38 DEO2 ( adsr )
    #0002   #3a DEO2 ( len )
    ;square #3c DEO2 ( addr )
    #ff     #3e DEO  ( volume )

    ( set up bass )
    #0600   #48 DEO2 ( adsr )
    #0002   #4a DEO2 ( len )
    ;square #4c DEO2 ( addr )
    #ff     #4e DEO  ( volume )

    ( set up callback )
    ;on-screen #20 DEO2
    BRK

@play ( dev^ track* -> )
    .position LDZ2 ADD2 LDA
    DUP ?&sound POP !&rest &sound SWP DEO JMP2r
    &rest POP JMP2r

@on-screen
    .counter LDZ ?&skip
    #3f ;treble play
    #4f ;bass play
    .position LDZ2k INC2 #00c0 DIV2k MUL2 SUB2 ROT STZ2
    &skip .counter LDZk INC #0b DIVk MUL SUB SWP STZ
    BRK

@square ff 00

@treble
    [ 40 00 3b 3c ] [ 3e 00 3c 3b ] [ 39 00 39 3c ] [ 40 00 3e 3c ]
    [ 3b 00 00 3c ] [ 3e 00 40 00 ] [ 3c 00 39 00 ] [ 39 00 00 00 ]
    [ 00 3e 00 41 ] [ 45 00 43 41 ] [ 40 00 00 3c ] [ 40 00 3e 3c ]
    [ 3b 00 3b 3c ] [ 3e 00 40 00 ] [ 3c 00 39 00 ] [ 39 00 00 00 ]

    [ 40 00 3b 3c ] [ 3e 00 3c 3b ] [ 39 00 39 3c ] [ 40 00 3e 3c ]
    [ 3b 00 00 3c ] [ 3e 00 40 00 ] [ 3c 00 39 00 ] [ 39 00 00 00 ]
    [ 00 3e 00 41 ] [ 45 00 43 41 ] [ 40 00 00 3c ] [ 40 00 3e 3c ]
    [ 3b 00 3b 3c ] [ 3e 00 40 00 ] [ 3c 00 39 00 ] [ 39 00 00 00 ]

    [ 40 00 00 00 ] [ 3c 00 00 00 ] [ 3e 00 00 00 ] [ 3b 00 00 00 ]
    [ 3c 00 00 00 ] [ 39 00 00 00 ] [ 38 00 00 00 ] [ 3b 00 00 00 ]
    [ 40 00 00 00 ] [ 3c 00 00 00 ] [ 3e 00 00 00 ] [ 3b 00 00 00 ]
    [ 3c 00 00 00 ] [ 39 00 00 00 ] [ 38 00 00 00 ] [ 3b 00 00 00 ]

@bass
    [ 28 00 00 00 ] [ 28 00 00 00 ] [ 2d 00 00 00 ] [ 2d 00 00 00 ]
    [ 2c 00 00 00 ] [ 28 00 00 00 ] [ 2d 00 00 00 ] [ 00 00 00 00 ]
    [ 26 00 00 00 ] [ 26 00 00 00 ] [ 24 00 00 00 ] [ 24 00 00 00 ]
    [ 28 00 00 00 ] [ 28 00 00 00 ] [ 2d 00 00 00 ] [ 00 00 00 00 ]

    [ 28 00 00 00 ] [ 28 00 00 00 ] [ 2d 00 00 00 ] [ 2d 00 00 00 ]
    [ 2c 00 00 00 ] [ 28 00 00 00 ] [ 2d 00 00 00 ] [ 00 00 00 00 ]
    [ 26 00 00 00 ] [ 26 00 00 00 ] [ 24 00 00 00 ] [ 24 00 00 00 ]
    [ 28 00 00 00 ] [ 28 00 00 00 ] [ 2d 00 00 00 ] [ 00 00 00 00 ]

    [ 2d 00 00 00 ] [ 2d 00 00 00 ] [ 2c 00 00 00 ] [ 2c 00 00 00 ] 
    [ 2d 00 00 00 ] [ 2d 00 00 00 ] [ 2c 00 00 00 ] [ 00 00 00 00 ] 
    [ 2d 00 00 00 ] [ 2d 00 00 00 ] [ 2c 00 00 00 ] [ 2c 00 00 00 ] 
    [ 2d 00 00 00 ] [ 2d 00 00 00 ] [ 2c 00 00 00 ] [ 00 00 00 00 ]