An apparatus for initiating partial transactions in a peripheral interface circuit for an I/O node of a computer system. An apparatus for performing partial transfers on a peripheral bus in response to a request for a stream of data includes a data buffer coupled to a control unit. The data buffer may be configured to store one or more data packets each containing data forming a portion of the data stream. The control unit may be configured to determine the presence of data packets stored in the data buffer that collectively contain a sequence of data forming a portion of the data stream. The control unit may be further configured to cause the sequence of data to be conveyed on the peripheral bus.