playing sound samples

[nitrofurano]

i found this version from http://www.msx.org/forumtopic5246p16.html, which the only difference would be the i/o port and the used bit flag for 1bit sound - this version seems to be simpler, and playing the sample in a straight direction, instead of that previous YourSinclair reversed example - i only couldn't understand how the 8 bits of each byte are being readed to be performed as 1bit sound (i think some instructions are missing there, and the 7 bits else from each byte are being wasted?)

Code:

    DEFB #FE
    DEFW BEGIN
    DEFW END
    DEFW BEGIN

    ORG #D000

BEGIN:

    LD HL,PLAY
    LD (#F39A),HL
    RET

PLAY:
    DI
    LD HL,#C000
    LD BC,#1000

PLAYLOOP:
    LD A,(HL)
    INC HL

    ADD A,A
    LD A,0
    ADC A,14
    OUT (#AB),A

    EXX
    LD B,60
WAIT:    DJNZ WAIT
    EXX
    DEC BC
    LD A,B
    OR C
    JP NZ,PLAYLOOP

    RET
END: