Method and apparatus for fixed latency subtractive decoding

A method comprising:

• sensing a first bus transaction initiation;
• speculatively acknowledging the first bus transaction within a predetermined time period from the first bus transaction initiation;
• sensing a retry signal for the first bus transaction within the predetermined time period from the first bus transaction initiation;
• and
• disregarding the first bus transaction responsive to sensing the retry signal.

An apparatus comprising:

• a bus;
• a positive decoding device coupled with the bus to acknowlege a first bus transaction for a first address range within a first time period;
• and
• a subtractive decoding device coupled with the bus to acknowlege a second bus transaction within a second time period substantially equal to the first time period.

An apparatus comprising:

• a bus interface to sense initiation of a first bus transaction;
• acknowledge logic coupled with the bus interface to assert a first acknowledge signal responsive to sensing the initiation of the first bus transaction;
• and
• subtractive decoding logic coupled with the bus interface to sense a second acknowledge signal and to disregard the first bus transaction responsive to sensing the second acknowledge signal.

An apparatus comprising:

• a bus interface to sense initiation of a first bus transaction;
• acknowledge logic coupled with the bus interface to transmit a first acknowledge signal responsive to sensing the initiation of the first bus transaction;
• and
• subtractive decoding logic to sense a retry signal and to disregard the first bus transaction responsive to sensing the retry signal.

An article of manufacture comprising:

• a machine-accessible medium including data that, when accessed by a machine, causes the machine to:
• speculatively assert a first acknowledge signal to acknowledge a bus transaction;
• and
• disregard the bus transaction when a second acknowledge signal is asserted.

A computing system comprising:

• a bus;
• a bus agent coupled with the bus to initiate a first bus transaction;
• a positive decoding device coupled with the bus to acknowledge the first bus transaction within a first time period from the initiation of the first bus transaction;
• and
• a subtractive decoding device coupled with the bus to speculatively acknowledge the first bus transaction within the first time period from the initiation of the first bus transaction.

A computing system comprising:

• a bus;
• a bus agent coupled with the bus to initiate a plurality of bus transactions;
• a positive decoding device coupled with the bus to acknowledge a first bus transaction of the plurality of bus transactions within a predetermined time period from the initiation of the first bus transaction;
• and
• a subtractive decoding device coupled with the bus to acknowledge a second bus transaction of the plurality of bus transactions within the same predetermined time period as the positive decoding device from the initiation of the second bus transaction.