Abstract: An apparatus for providing packets in a peripheral interface circuit of an I/O node of a computer system. The apparatus includes a buffer that may be configured to accumulate data received on a first bus. The apparatus further includes a control unit coupled to the buffer which may be configured to transmit a data packet containing a first number of bytes of the data in response to detecting that any of the bytes of the data is invalid. The control unit may be further configured to transmit the data packet containing a second number of bytes of the data in response to detecting that all of the bytes are valid.

Abstract: A circuit and method for correcting erroneous data in memory for pipelined reads. A memory controller includes a control unit, a storage unit and an error detection and correction unit. The control unit is configured to read data including an associated error correction code from a memory subsystem in response to a memory read request. The error detection and correction unit is coupled to receive the data and configured to determine whether an error exists in that data based upon the associated error correction code. The control unit is configured to store an indication in the storage unit that the data corresponding to the memory read request is erroneous. The control unit is further configured to detect the indication in the storage unit and to responsively perform a subsequent read of the data from the memory subsystem and to write a corrected version of the data back to the memory subsystem.

Abstract: A method and apparatus for reducing latency in a peripheral interface circuit of an I/O node of a computer system. The apparatus includes a buffer coupled to a control unit. The buffer may be configured to receive data on a first bus and the control unit may be configured to generate a first command type in response to receiving a first quantity of data having invalid bytes within the buffer. The control unit may be further configured to generate a second command type in response to a receiving within the buffer a second quantity of data having no invalid bytes. Further, in response to receiving a particular transaction type, the control unit may be configured to generate the second command type before the first quantity of data is received within the buffer.

Abstract: An apparatus for reordering graphics responses in a peripheral interface circuit for an I/O node of a computer system. The apparatus includes a data buffer and a control unit. The data buffer includes a first plurality of storage locations each corresponding to one of a plurality of tag values. The data buffer may receive a plurality of data packets associated with the graphics transactions. The data buffer may also store the data packets in the storage locations according to tag values. The control unit includes a storage unit having a second plurality of locations. Each of the locations in the storage unit corresponds to one of the tag values and may provide an indication of whether a given data packet has been stored in the data buffer. The control unit may further determine an order in which the plurality of data packets is read from the data buffer.

Abstract: A peripheral interface circuit for an I/O node of a computer system. A peripheral interface circuit for an input/output node of a computer system includes a first buffer circuit, a second buffer circuit and a bus interface circuit. The first buffer circuit receives packet commands and may include a first plurality of buffers each corresponding to a respective virtual channel of a plurality of virtual channels. The second buffer circuit is coupled to receive packet commands from the bus interface circuit and may include a second plurality of buffers each corresponding to a respective virtual channel of the plurality of virtual channels. The bus interface circuit may be configured to translate selected packet commands stored in the first buffer circuit into commands suitable for transmission on a peripheral bus.

Abstract: A microcontroller is provided with one or more synchronous serial channels, such as HDLC channels, that are coupled to time slot assigners for communication over a time division multiplex bus. The time slot assigners each include a bit position start register and a bit position stop register that allows the time slot assigner to enable and disable the associated synchronous serial channel on the arrival of a specific bit position within the time division multiplex bus frame. Further, an end of slot adjust register provides for additional bits to be placed by the time slot assigner on to the end of a slot that is transmitted by an associated synchronous serial communication channel transmitter.

Abstract: A microcontroller integrates an internal memory accessible by the cores included thereon. Logic within the microcontroller compares memory addresses generated by the cores to values in a configuration register specifying a memory address range in which the internal memory resides. The logic generates a chip select signal to the internal memory if the memory address generated resides within the specified address range to enable accesses by the cores to the internal memory. The integrated circuit may be configured in a debug mode wherein the chip select signal is inhibited to the internal memory, however the chip select signal is provided external to the integrated circuit on a pin. The chip select signal may then be used to select an external memory which serves to overlay the internal memory address range. Thus the debug mode allows instruction code and data to reside in the external memory rather than the internal memory while in the debug mode.