Buffering of non-posted read commands and answers

An improved interface technology for use in a South Bridge or I / O hub, or in similar devices is provided, received at the non-posted read requests from at least a requesting entity and upstream data is transmitted on the basis of these requirements. Reply data is received in response to commands that have been sent before, and responses are sent on the basis of the response data to the at least one requesting unit. A buffer device is provided for storing instruction identification data identifying the commands that are sent or waiting to be sent, and for storing response availability data specifying the response data which have been received by the receiving means. The improvement may allow multiple outstanding read requests.