HP Vectra Technical Reference Manual page 444

SF_OPEN (AX
=
020EH)
Allows exclusive access to this driver. All resources required for driver operation will be acquired
at this time. This function has special meaning for the the HP-HIL driver, the HPIB driver and the
HPIL driver. Since these drivers support shared interfaces, control of the resource HP-HIL
(obtained from the driver V_HPHIL), control of the HPIB (in contention with other PC's on the
bus), and control of the HPIL (in contention with other PC's on the loop) is requested and
obtained. Control should be kept until a single operation is performed on the resource. A status
of RS_BUSY will be reported if thl= device has previously been opened. RS_SUCCESSFUL will be
reported if the device is available.
)~
busy status does not prevent access to the driver. All
functions will execute (perhaps improperly) whether a driver has been opened or not.
On Entry: AH
=
F_SYSTEM (02H)
AL
=
SF_OPEN (OEH)
BP
=
Driver's vector address
On Exit: AH
=
Return Status Code
SF_CLOSE (AX
=
0210H)
Closes the requested resource. Again this function has special meaning for the interface class of
devices, HPIB, HP-HIL, and HPIL. The driver goes to a state where control can be obtained
by
or
passed to another controller.
On Entry: AH
=
F__SYSTEM (02H)
AL
=
SF_CLOSE (1
Or~)
BP
=
Driver's vector address
On Exit: AH
=
Return Status Code
SF_TIMEOUT (AX
=
0212H)
Reports to the driver that its timer event number has occurred.
On Entry: AH
=
F_SYSTEM (02H)
AL
=
SF_TIMEOUT (12H)
~
BP
=
Driver's vector address
On Exit: AH
=
Return Status Code
Driver V\lriter's Guide 435