Technical information

Serial Solutions NewBIOS Reference
Service 2H, Receive Character.___________________________
Compatibility._____________
This Service is fully compatible with the PC ROM BIOS.
Parameters.___________
AH = 2H Denotes service 2H
DX = 0...31 Port number 0=COM1...31=COM32
Return Values._____________
AH is 16450 Line status or time_out,
where
bit 7 = Time-out. If true then remaining bits
are undefined
bit 6 = 0
bit 5 = 0
bit 4 = Break interrupt
bit 3 = Framing error
bit 2 = Parity error
bit 1 = Overrun error
bit 0 = 0
AL is Character received.
Meaning._________
Service 2H waits for a character to arrive from the serial
port. As service 1H it first performs an RS232 handshake by
setting DTR and clearing RTS, and waits for DSR to go true. A
time-out is returned if it does not. The service then waits for the
16450 to receive a character, and either returns it or a time-out.
The line status returned in AH can be used to check for receiver
errors such as a parity error.
Other Points.____________
Page 80 Chapter 5