Service manual

1.2 System Functional Description
The <REFERENCE>(2X) systems support multiprocessing with
up to six <REFERENCE>(xyp) or <REFERENCE>(XRP) pro-
cessors. The system uses a high-speed <REFERENCE>(XMI)
system bus to connect its processors, its memory modules,
and its I/O adapters.
Figure 1–1: <REFERENCE>(2X) System Architecture
KDM70
CIXCD
DEMNA
ETHERNET
AND CD SERVER
XMI
MEMORY
PROCESSORS
msb-0310-90
DISKS
AND TAPES
STAR
COUPLER
VAXBI
DWMBB/A
DWMBB/B
OPTION
The <REFERENCE>(XMI) is the 64-bit system bus connecting all major
subsystems. It has a maximum throughput of 100 Mbytes per second.
Early versions of the VAX 6000 series had no direct XMI I/O. I/O was
achieved through an interface between the XMI bus and the VAXBI bus
which had direct I/O to the CI, disks, tapes, and other I/O devices. Since
direct XMI I/O now exists, the VAXBI is now optional.
The VAXBI and <REFERENCE>(XMI) share the concept of a node. A
node is a single functional unit that consists of one or more modules. The
1–4 VAX 6000 Models 300 and 400 Service Manual