Fnumcalc.exe -------- A simple program that calculates Frequency numbers 
                      for various FM chips, and for the PSG on the Genesis/Megadrive.
                      The PSG F-Num is given in two formats:  the actual number put in
                      the register, and the format used in BasiEgaXorz(BEX).

mdfmedit.exe -------- A program that lets you make instrument patches for the Genesis
                      You can even hear what it sounds like immediately.
                      This program requires X68Sound.dll


X68Sound.dll can be aquired at http://homepage1.nifty.com/mpuusan/x68sound/x68soundbody.htm
The file you want is "X68Sound_020615.zip"