Hyperplane Crossbar-Routing Attachment Controller - HP 9000 V-Class Operator's Manual

Overview
The node
The EPAC includes special hardware called the data mover for rapid
message and data movement between memory within a node. This
dedicated hardware greatly improves file I/O and networking over
software versions.
Hyperplane crossbar—routing attachment controller
The Hyperplane crossbar is comprised of four ERACs that provide an
interconnect for each processor and I/O device to memory.
Each of the four ERACs has the following buses:
EPAC Port (A, B, C, D)—Eight 32-bit, unidirectional interfaces to four
EPAC ports, four in each direction. Each port has simultaneous (input
and output) bandwidth of 960 Mbytes/sec.
EMAC Port (A, B, C, D)—Eight 32-bit, unidirectional interfaces to four
EMAC ports, four in each direction. Each port has simultaneous (input
and output) bandwidth of 960 Mbytes/sec.
Figure 2 shows how the ERACs connect to each EPAC and EMAC.
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