The VXIbus specification confers special status and functionality on the leftmost slot (slot-0). It includes unique backplane wiring e.g. for geographical addressing and is required to provide clock generation (10 MHz clock C- and D-size, and 100 MHz D-size). It is responsible for performing the Resource Manager Function at startup. In general the Slot-0 must either contain a processor its self or have a link to a processor capable of executing the resource manager function. Various implementations of the slot-0 are available including both intelligent controllers as well as controllers that are linked back to an independent computer system.
The slot-0 is responsible for carrying out the resource manager function at power up. This includes the following:
- Identify all VXIbus devices in the mainframe.
- Manage the system self test and diagnostic sequence.
- Configure the system's A24 and A32 address maps.
- Allocate the VMEbus IRQ lines.
- Initiate normal system operation.