Specifications

Loading an OpenVMS AXP Device Driver
10.1 Manually Connecting Devices and Loading Drivers
10.1.2 Obtaining the Adapter’s CSR Address
When connecting a device, the driver loading procedure creates a UCB, CRB,
and IDB for it and copies the value of the csr parameter of the IO CONNECT
command directly to the IDB$Q_CSR field in the IDB.
In general, when manually connecting a device, you should specify the base CSR
address of the device register space. As is the case with the adapter TR number
used in the adapter parameter, the base CSR of each adapter is part of the
display provided by the IO SHOW BUS command.
The CSR address format differs from bus to bus. The IO SHOW BUS output
shows the CSR address in the proper format for the bus being displayed. Locate
your adapter in the IO SHOW BUS display and use the associated CSR address
in the IO CONNECT command.
10.1.3 Locating the Adapter’s Interrupt Vectors
The assignment of vectors to adapters is bus-specific, as follows:
• XMI
On the XMI, vectors are assigned to adapters during bus probing.
A future release of SYSMAN will automatically find the vectors for the
adapter specified in the adapter parameter for manual connections of XMI
adapters. As a result, you will not need to specify the vector parameter for
these adapters.
• Futurebus+
In general, Futurebus+ adapters require blocks of vectors with an alignment
constraint on the base vector. Vectors are not assigned to adapters during bus
probing (in contrast to XMI).
A future release of SYSMAN will automatically allocate the number of vectors
specified in the num_vec parameter for manual connections of Futurebus+
adapters. For more information, see Chapter 15.
• TURBOchannel
On the TURBOchannel, vectors are associated with TURBOchannel
backplane slots. TURBOchannel adapters do not have programmable vector
registers (as do XMI and Futurebus+ adapters). Rather, the slot into which
the adapter is plugged determines the vector it uses for interrupts. A side
effect of this is that TURBOchannel adapters are restricted to using a single
interrupt vector.
The algorithm for determining slot/vector correspondence is simple:
vector = slot_number * 4
The node number is part of the IO SHOW BUS display. Node number and
slot number are identical concepts for TURBOchannel adapters. Thus, if you
locate your adapter in the IO SHOW BUS display, you can use the associated
node number to calculate the vector location.
10–2