Specifications

Device Driver Entry Points
Unit Initialization Routine
Input
Location Contents
R3 Address of primary CSR.
R4 Address of secondary CSR, if it exists. (If it does
not, the contents of R4 are the same as those of R3.)
R5 Address of UCB.
Exit
The unit initialization routine returns control to its caller with an RSB
instruction.
Description
Depending on the device, a unit initialization routine performs any or all of the
following tasks:
1. Determines whether it is being called as a result of a power failure by
examining the power bit (UCB$V_POWER in UCB$L_STS) in the UCB. A
unit initialization routine may want to perform or avoid specific tasks when
servicing a power failure.
2. Clears error-status bits in device registers.
3. Enables controller interrupts.
4. Sets the online bit (UCB$V_ONLINE in UCB$L_STS).
5. Allocates resources that must be permanently allocated to the device or, for
some devices, the controller.
6. If the device has a dedicated controller, as some printers do, fills in IDB$L_
OWNER.
7. For dedicated VAXBI controllers, initializes BIIC and device hardware.
8. For multiunit VAXBI controllers, tests for the existence of the unit for which
it was called and returns success or failure status to SYSGEN.
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