( Borrowed from http://wikiti.brandonw.net/ )
( Divides AC by DE and places the quotient in AC and the
  remainder in HL )
CODE /MOD EXX, ( protect BC )
    DE POP, BC POP, chkPS,
    A B LDrr, B 16 LDri,
    HL 0 LDdi,
    BEGIN,
        SCF, C RL, RLA,
        HL ADCHLd, DE SBCHLd,
        IFC, DE ADDHLd, C DECr, THEN,
    DJNZ, AGAIN,
    B A LDrr,
    HL PUSH, BC PUSH,
EXX, ( unprotect BC ) ;CODE