Int 61 Fn 21  - PC/tcp Kernel V2.05+ - "get_option" - Get Options Applied  [N]

   AH = 21h
   BX = network descriptor
   CX = length of buffer
   DS:DX -> buffer for return values
   SI = 0004h (ignored by v2.2-)
   DI = option (see AH=20h)

Return: CF clear if successful
       DS:DX -> value (usually 32 bits) returned by selected option
   CF set on error
       AX = error code (see INT 61"PC/TCP")

Note:  this function is not supported by Beame&Whiteside's BWPCTCP v3.0a shim

See Also: INT 61"PC/TCP",INT 61/AH=00h"PC/TCP",INT 61/AH=20h