REVRSN  START
        PUSH     0,GR1
        PUSH     0,GR2
        LAD      GR2,-1,GR1  ;最終語のアドレス → GR2
        ADDA     GR2,GR0
LP      LD       GR0,0,GR1   ;始めの語
        CALL     REVRS
        ST       GR0,WORK1
        LD       GR0,0,GR2   ;後ろの語
        CALL     REVRS
        ST       GR0,0,GR1
        [    ( c )    ]
        ST       GR0,0,GR2
        LAD      GR1,1,GR1
        LAD      GR2,-1,GR2
        CPA      GR2,GR1
        [    ( d )    ]
        JZE      LP
        POP      GR2
        POP      GR1
        RET
WORK1   DS       1
        END