CODE * EXX, ( protect BC )
    ( DE * BC -> DE (high) and HL (low) )
    DE POP, BC POP, chkPS,
    HL 0 LDdi,
    A 0x10 LDri,
    BEGIN,
        HL ADDHLd,
        E RL, D RL,
        IFC,
            BC ADDHLd,
            IFC, DE INCd, THEN,
        THEN,
        A DECr,
    JRNZ, AGAIN,
    HL PUSH,
EXX, ( unprotect BC ) ;CODE