Int 14 Fn 06  - Telapi - Write Block                                       [N]

   AH = 06h
   CX = number of characters to write
   DX = port number
   ES:DI -> buffer containing data

Return: AX = number of characters actually sent (negative on error)
   CX = ???

See Also: AH=07h"TelAPI",AH=E0h"TelAPI",AH=E3h"TelAPI"