SWAP10  START   100
FIRST   LDX     #0
READL   TD      INDEV
        JEQ     READL
        RD      INDEV
        STCH    INPUT,X
        TIX     LEN
        JLT     READL
        LDX     #0
SWAPL   LDT     INPUT,X
        LDA     LEN
        SUB     X
        SUB     #3
        STT     OUT,A
        ADDR    #2,X
        TIX     LEN
        JLT     SWAPL
INPUT   RESW    100
OUT     RESW    100
LEN     WORD    300
INDEV   BYTE    X'F1'
        END     FIRST