US 5,515,516 A · Initialization mechanism for symmetric arbitration agents

Abstract

An initialization mechanism for symmetric arbitration agents ensures that multiple agents on a bus are each initialized with a different arbitration counter value. The arbitration counter of each bus agent is used to keep track of which agent was the last or current owner of the bus and which agent will be the next owner of the bus. All bus agents agree on which agent will be the priority agent at system reset and thus be allowed first ownership of the bus. Each agent's arbitration counter is initialized according to each agent's own agent identification. The arbitration pins of the bus agents are interconnected such that each agent determines for itself a unique agent identification based on which pin of its arbitration pins is active at system reset and the maximum number of bus agents allowed on the bus. After determining its agent identification, each bus agent initializes its arbitration counter such that every agent agrees which agent is the priority agent. Each agent performs this initialization based on its agent identification, the identity of the priority agent, and the maximum number of agents allowed on the bus.

Claims41

Dependent claims

An apparatus comprising:

a bus;
logic coupled to said bus for providing an initialization signal;
and
one or more agents coupled to said bus, wherein each respective agent includes,
a first circuit for determining,
which of said one or more agents will be a first agent having priority, to own said bus,
a unique identification for said respective agent,
an initial priority for said respective agent,
a second circuit, coupled to said first circuit, for storing a value identifying said initial priority for said respective agent determined by said first circuit,
a third circuit, coupled to said second circuit, for altering the value stored in said second circuit to identify another agent as a current bus owner, and
a fourth circuit, coupled to said second circuit, for detecting whether said value stored in said second circuit identifies said respective agent as the current bus owner, and for permitting or denying said respective agent to access said bus, accordingly.

8 more elements

A computer system comprising:

a system bus;
a request bus having a plurality N of bus request lines;
power-on logic coupled to said request bus, and coupled to receive a reset signal upon initialization of the computer system;
and
at least one symmetric agent coupled to said system bus, each respective agent including,
N inputs coupled to respective ones of said N bus request lines in a unique pattern of rotating interconnect,
an arbitration counter,
an agent identification register,
initialization logic coupled to said N inputs, said arbitration counter, and said agent identification register, and coupled to receive said reset signal, said initialization logic for determining a maximum number of symmetric bus agents which may be coupled to said bus, for storing a unique agent identification value into said agent identification register upon receipt of said reset signal and according to said unique pattern of rotating interconnect of the respective agent such that each agent will have a unique agent identification, and for storing a priority value into said arbitration counter upon receipt of said reset signal such that each agent will store a priority value identifying a given one agent as an initial bus master.

6 more elements

A computer system comprising:

a first bus coupled to a second bus;
a first logic coupled to said first bus for providing a first initialization signal;
a first agent coupled to said first bus, said first bus agent including a first circuit for determining,
a first agent having priority to own said first bus,
a first identification for said first agent based on which input of a first plurality of inputs receives said initialization signal, and
an initial priority for said first agent;
a second logic coupled to said second bus for providing a second initialization signal;
and
a second agent coupled to said second bus, said second agent including a second circuit for determining,
a second agent having priority to own said second bus,
a second identification for said second agent based on which input of a second plurality of inputs receives said initialization signal, and
an initial priority for said second agent.

9 more elements

Dependencies are inferred from the claim text.

Initialization mechanism for symmetric arbitration agents

Life of this patent

Initialization mechanism for symmetric arbitration agents

Life of this patent

Abstract

Claims41