Buffering non-posted read commands and responses

An integrated circuit chip comprising:

• a transmit circuit adapted to receive non-posted read requests from at least one requestor, and transmit upstream commands based on said non-posted read requests;
• a receive circuit adapted to receive response data in reply to commands previously transmitted by said transmit circuit, and transmit responses to said at least one requester based on said response data;
• and
• a buffer unit connected to said transmit circuit and said receive circuit, said buffer unit being adapted to store command identification data identifying commands transmitted or to be transmitted by said transmit circuit, and response availability data specifying response data that has been received by said receive circuit.

A computer system comprising:

• at least one peripheral component;
• and
• a southbridge comprising a transmit engine adapted to receive non-posted read requests from at least one peripheral component controller, and transmit upstream commands based on said non-posted read requests;
• and a receive engine adapted to receive response data in reply to commands previously transmitted by said transmit engine, and transmit responses to said at least one peripheral component controller based on said response data;
• wherein said southbridge further comprises a buffer unit connected to said transmit engine and said receive engine, said buffer unit being adapted to store command identification data identifying commands transmitted or to be transmitted by said transmit engine, and response availability data specifying response data that has been received by said receive engine.

A method of operating a southbridge device, the method comprising:

• receiving non-posted read requests from at least one requester;
• transmitting upstream commands based on said non-posted read requests;
• receiving response data in reply to previously transmitted commands;
• and
• transmitting responses to said at least one requestor based on said response data,
• wherein the method further comprises:
• storing command identification data identifying transmitted or to be transmitted commands;
• and
• storing response availability data specifying received response data.