Int E0  - Real/32 - "n_errmode" - Set Network Error Mode                   [O]

   CL = 48h
   DL = new error mode
       FFh return error in registers AX,BX,CX
       FEh display message and return error
       FDh display message and abort (default)

Return: CX = error code (0000h successful, FFFFh failed)
   may destroy SI,DI???
Desc:  specify how the REAL/32 Net Server responds to error numbers 0CFFh,
     0DFFh, and 0EFFh (see #3696)