HP Vectra Technical Reference Manual page 235

F14__RECV (AH
=
02H)
This function reads a data byte from the serial port specified by the DX register. The signal
DATA-TERMINAL-READY is enabled in the modem control register indicating to the remote
device that data can be sent. The modem status register signal DATA-SET-READY and the line
status register signal DATA-READY are polled until a data byte is available to read or the timeout
count has expired.
On Entry: AH
=
F14_RECV (02H)
DX
=
Port number (0, 1, 2, 3)
On Exit: AH
=
Line status (see table 7.5)
AL
=
If no error: Data byte received
If error: Null character, zero
Registers Altered: AX
Example:
MOV AH, F14__RECV ,. (AH
=
2)
MOV DX,
0 ,.
Port
0
specification
INT INT_SERIAL ,. Call serial driver (lNT 14H)
TEST AH, 100000008 ,. Check for error
JNZ short ERROR_RECEIVE
F14__STATUS (AH
= 03H)
This subfunction returns the status of the serial port specified by the DX register.
On Entry: AH
=
F14__STATUS (03H)
DX
=
Port number (0, 1, 2, 3)
On Exit: AH
=
Line status (see table 7.5)
AL
=
Modem status (see table 7.6)
Registers Altered: AX
F14__INQUIRE (AX
=
6FOOH)
This function determines whether or not the extended EX-BIOS functions are available. If the
EX-BIOS functions are available, the BX register will be set to 4850H (which are the ASCII
characters 'HP').
226 Serial and Parrallel I/O