This also uses a simple C optimisation by setting a local variable to the contents of the table before entering a loop as in this fragment:

powTen = PowTenTbl[i];
   while (bin >= powTen)
   {
       bin -= powTen;
       digit++;
    }

This saves having to look up the table each time through the loop.

And a question - in this fragment:

for (i = 0; i != DIM(PowTenTbl); i++)

Did you mean i <= DIM(PowTenTbl) ?

Ian