Int 14 Fn 8C  - Comm-drv V14.0 - Read Uart Register                        [S]

   AH = 8Ch
   AL = register offset
   DX = port number

Return: AH bit 7 set on error
   AH bit 7 clear if successful
       AL = contents of UART register

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