Here's a BASIC statement that converts a DECIMAL address
   (DA) from 0 to 65535 into the necessary NUMERIC VARIABLE
   equivalent (NV%):
   100 NV%=DA+65536*(DA>32767)

   WHERE'S PROMOS?

       As you use the M command to browse through memory, you
   come across nothing resembling a sizeable machine language
   program. So where's PROMOS? It's tucked away in RAM under
   the Kernal at E000. Operating from there, it leaves
   everything else available to you. There are a few bytes of
   code well down on the stack which take care of switching
   things in and out. In 64 mode, PROMOS hooks in through
   IGONE. In 128 mode, ICRNCH is taken over as well.

   TROUBLESHOOTING

       The frustrations that can arise programming balky EPROM's
   can often be avoided by making sure of a few things:

       Make sure your EPROM is erased. Use the D, A or E
   commands for a quick check.

       Make sure your EPROM is seated properly in the socket and
   is making contact at all pins.

       Make sure your programming command Is correct.
   Especially check the CONTROL WORD. If you use an incorrect
   one you can destroy your EPROM.

       Make sure your PROMENADE is making good contact with the
   user port connector. The board-edge surfaces may need
   cleaning. An easy way to do this is to go over them lightly
   with a pencil eraser.

       Make sure your power supply is in good shape. Commodore
   64 power supplies have a tendency to get tired after a while.

       You may wish to try a modified programming method that
   turns off Vpp during read-back as discussed in Appendix B.



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