CODE S= EXX, ( protect BC )
    DE POP, HL POP, chkPS,
    LDA(DE),
    (HL) CPr,
    IFZ, ( same size? )
        B A LDrr, ( loop A times )
        BEGIN,
            HL INCd, DE INCd,
            LDA(DE),
            (HL) CPr,
            JRNZ, BREAK, ( not equal? break early. NZ is set. )
        DJNZ, AGAIN,
    THEN,
    PUSHZ,
EXX, ( unprotect BC ) ;CODE