Int 14 Fn 8D  - Comm-drv V14.0 - Write Uart Register                       [S]

   AH = 8Dh
   AL = register offset
   BL = new value for UART register
   DX = port number

Return: AH bit 7 set on error
   AH bit 7 clear if successful

See Also: AH=8Ch"COMM-DRV"