Owner`s manual

The system bus, the XMI, allows several transactions to occur

simultaneously, making efﬁcient use of the bus bandwidth. The bus

includes the XMI backplane, the electrical environment of the bus, the

protocol that nodes use on the bus, and the logic to implement this protocol.

The 14-slot XMI card cage is located in the upper third of the cabinet on

the right side, as viewed from the front of the cabinet. A clear latched

door protects the components housed in the card cage and helps to direct

the airﬂow over the modules. Indicator lights on the XMI modules can be

viewed through this clear front door. The protective door must be closed

for operation, as it controls the power supply to the card cage.

Each slot of the XMI card cage is hardwired to a 4-bit node ID code that

corresponds to the physical slot number in the card cage. The node ID

number of the module is its slot position. The slots are numbered 1 through

E (hexadecimal) from right to left, as you view the card cage from the front

of the cabinet.

For information on XMI card cage conﬁguration rules and module indicator

lights, see the VAX 6000 Platform Service Manual. The VAX 6000 Platform

Technical User’s Guide gives in-depth information on the operation of the

system bus.

System Components 2–11