Technical information

NewBIOS Reference Serial Solutions
= 03H 600 Baud
= 04H 1,200 Baud
= 05H 2,400 Baud
= 06H 4,800 Baud
= 07H 9,600 Baud
= 08H 19,200 Baud
= 09H 38,400 Baud (NewBIOS only)
= 0AH 57,600 Baud (NewBIOS only)
= 0BH 115,200 Baud (NewBIOS only)
DX = 0...31 Port number, 0=COM1...31=COM32
Return Values._____________
AH is 16450 Line status, where
bit 7 = 0, always
bit 6 = Transmitter shift register empty
bit 5 = Transmitter holding register empty
bit 4 = Break interrupt
bit 3 = Framing error
bit 2 = Parity error
bit 1 = Overrun error
bit 0 = Data ready
AL is 16450 modem status, where
bit 7 = DCD, Data Carrier Detect
bit 6 = RI, Ring Indicator
bit 5 = DSR, Data Set Ready
bit 4 = CTS, Clear To Send
bit 3 = Delta DCD, set true if bit 7 has
changed since last read
bit 2 = Delta RI " " " " 6 " " " " "
bit 1 = Delta DSR " " " " 5 " " " " "
bit 0 = Delta CTS " " " " 4 " " " " "
These return values for AL, AH are the same as for
services 0H, 3H and 5H (they are generated by the same piece
of code).
Chapter 5 Page 85