Compaq 320 - Manual (Page 9)

Overview 1-1
Chapter 1
Overview
The AlphaServer GS80, GS160, and GS320 systems are high-performance
server platforms designed for enterprise-level applications. They are
distinguished by their versatility and high degree of scalability and
expandability.
These powerful, switch-based systems use four Alpha microprocessors per quad
building block (QBB). Two QBBs paired back-to-back and rotated 180
0 with
reference to each other form a system box. Each QBB backplane contains a
switch that acts as an interconnect between the CPU modules, memory
modules, I/O riser modules, and the global port module.