LDY #$00
LOOP    LDA STRING,Y
        BEQ EXIT
        JSR $FFD2
        INY
        JMP LOOP
EXIT    RTS
STRING  .DB 'HELLO WORLD'
        .DB 0

Absolute,X    LDA $4400,X   $BD  3   4+
Absolute,Y    LDA $4400,Y   $B9  3   4+