INT 7F - Alloy MW386 - SET TERMINAL PARAMETERS
        AH = 3Bh
        AL = baud rate (00h = 38400, 01h = 19200, etc)
        CL = parity (00h none, 01h even, 02h odd)
        CH = handshaking (00h none, 01h XON/XOFF, 02h DTR/DSR, 03h XPC)
        DL = user number (FFh = caller)
        DH = machine number for user
Return: CF set if invalid user number
Notes:  only available to supervisors
        the new parameters will take effect immediately if the user's terminal
          has not been started, else AH=3Dh must be called to post the changes
SeeAlso: AH=3Dh