INT 14 - Digiboard - CCB COMMAND - SET TRANSMIT MID-WATER MARK AX = 164Dh BX = new mid-water mark CL = byte 1 DX = port number (00h-03h) (04h-43h for XAPCM232.SYS) Return: AH = status 00h successful 80h error FFh error SeeAlso: AH=16h"Digiboard",AX=164Ch,AX=164Eh,AX=164Fh