HP 9000 Series 300 Tutorials Manual page 160

hpib_status
The hpi b_status routine cannot sense lines being driven (output) by the
interface. In other words, listeners cannot senses NDAC and non-controllers
cannot sense SRQ.
When an HP-IB interface is reset via io_reset, the interrupt mask is set to 0,
the parallel poll response is set to 0, the serial poll response is set to 0, the
HP-IB address is assigned, the IFC line is pulsed (if system controller), the
card is put on line, and REN is set (if system controller).
When a GPIO interface is reset, the peripheral request line is pulled low, the
PTCL line is placed in the clear state, and if the DOUT CLEAR jumper is
installed, the data out lines are all cleared. The interrupt enable bit is also
cleared.
io_speed_ctl
If the I/O transfer speed is set less than 7Kb/sec (i.e., the speed parameter is
less than 7), then the interface will use interrupt transfer mode. If the transfer
speed is set greater than 140Kb / sec (speed
>
140), then the system chooses
the fastest mode possible. If the speed is between 7Kb and 140Kb/sec (7Kb
~
speed
~
140), then DMA transfer mode is used.
IMPORTANT
If you are using pattern termination, via io_eol_ctl, then
you'll always get interrupt mode, regardless of speed.
This routine allows you to set a time limit for I/O operations on an entity
identifier associated with an interface file. The timeout value that you
specify is a 32-bit long integer that indicates the length of the timeout
in microseconds. However, the resolution of the effective timeout is
system-dependent. On the Series 300 computers the timeout is rounded up to
the nearest 20-millisecond boundary. For example, if you specify a timeout of
A-8 Series 300 Dependencies