From:
         "Peter L. Peres" <plp@ACTCOM.CO.IL>

                                   high  mid  low
                                       ff    ff      01  - 1  =  ff  ff
00

   decf    mid, F               ff    fe     01
   decf    mid, F               ff    fd     01
   decfsz  low, F              ff    fd    00
   incf    mid, F                    skip
   incfsz  mid, F               ff    fe    00
   decf    high, F              fe    fe    00  !

Am I missing something here?