Appeal No. 2006-2217
Reexamination Control Nos. 90/006,789 and 90/007,420
for a specific operation onto the
Parallel System bus.
Replying Agent The agent or agents with which the
requesting agent performs a transfer
cycle. Replying agents respond to a
requesting agent during the transfer
cycle.
Read Operation The transfer of data from a replying
agent to a requesting agent.
Write OperationThe transfer of data from a requesting
agent to replying agents.
A block diagram of the iPSB Parallel System bus interface is
shown in Figure 1-2 (sheet 2-6). The "requesting agent" and the
"replying agent" are electrically coupled together through the
iPSB Parallel System bus.
Agents perform one of three types of bus cycles on the
Parallel System bus: an "arbitration cycle" is a time period in
which agents arbitrate and decide which one will have exclusive
access to the system bus; the "transfer cycle" is a subsequent
time period in which the agent that has won control of the bus
performs addressing and data transfer cycles to move data to or
from another agent; and an "exception cycle" is an
error-reporting time period that occurs only when an error is
sensed (sheets 2-8 through 2-12).
Only the transfer cycle is relevant here. The transfer
cycle includes a request phase and a reply phase. The transfer
cycle is described as follows (sheet 2-10):
The request phase is controlled by the bus owner. During
the request phase, the requesting agent places address and
control information onto the bus. The address and control
information defines the replying agent(s), the type of
operation, and the type of address space involved in the
transfer cycle.
After the requesting agent transmits the address and control
information, the reply phase of the transfer cycle begins,
in which the replying agent(s) satisfies the request.
During the reply phase, the requesting and replying agents
engage in a close handshake that synchronizes the data
transfer sequence. The requesting and replying agents may
perform one or more data transfers in a reply phase. The
final data transfer is accompanied by an end-of-cycle (EOC)
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