Abstract: A switched Ethernet controller (SEC) device and associated method that provides processor based intervention in the packet routing decision process is provided. The method of routing a multicast packet between a source port on a source device and a plurality of destination ports on a plurality of destination devices, utilizes a processor. The method includes the steps of the source device receiving the multicast packet via the source port, the source device sending the multicast packet to the processor, the processor examining the multicast packet, the processor determining the plurality of destination devices and corresponding the plurality of destination ports based on the results obtained during the step of examining, the processor transferring the multicast packet to the plurality of destination devices, and the plurality of destination devices sending the multicast packet to the plurality of destination ports.

Abstract: An Ethernet controller, for use within an Ethernet network of other Ethernet controller connected together by a bus, is provided. The Ethernet controller includes a plurality of ports including at least one bus port associated with ports connected to other switching Ethernet controllers, a hash table for storing addresses of ports within the Ethernet network, a hash table address control, a storage buffer including a multiplicity of contiguous buffers in which to temporarily store said packet, an empty list including a multiplicity of single bit buffers, a packet storage manager, a packet transfer manager and a write-only bus communication unit. The hash table address control hashes the address of a packet to initial hash table location values, changes the hash table location values by a fixed jump amount if the address values stored in the initial hash table location do not match the received address, and provides at least an output port number of the port associated with the received address.

Abstract: A structure and a method are provided to implement a reset scheme for an integrated circuit supporting a variety of testing and debugging equipment. The control and I/O pins of the integrated circuit are each set to a high impedance state when the signals of a reset pin and a mode pin are both asserted. If the signal on the mode pin remains asserted at the time the signal on the reset pin is negated, the control and I/O pins of the integrated circuit remain in the high impedance state until the next time the signal on the reset pin is asserted. Otherwise, the control and I/O pins of the integrated circuits are enabled upon negation of the signal on the reset pin. In one embodiment, the mode pin is multiplexed with an pin used for receiving interrupt signals during functional operation.

Abstract: A variable sized FIFO buffer whose size changes in accordance with how much data is present to be passed between the two systems is provided.One embodiment of the FIFO buffer includes at least one lower FIFO, at least one upper FIFO, a RAM and a controller. The upper FIFO buffer receives data from a first system and the lower FIFO buffer writes data to a second system. The RAM is utilized when data can no longer flow between the upper and lower FIFO buffers, due to the lower FIFO buffer being temporarily full.

Abstract: A multiple FIFO array which does not use numerous single FIFO devices is provided. The multiple FIFO array includes a memory partitioned into a plurality of N sections, each section corresponding to one of N FIFOs. The memory has a write address input, write strobe input, data input, read address input, read strobe and data output. Also included is a plurality of N write pointer registers, a write multiplexer having N write inputs, a write output and a write select input, a plurality of N read registers and a read multiplexer. Each write pointer register corresponds to one of N FIFOs and each write pointer register holds the write address corresponding to one of N FIFOs. The N write inputs of the write multiplexer are coupled to the output of the plurality of N write pointer registers, the write output is coupled to the write address input in the memory and the write select input couples one of the N write inputs to the write output.

Abstract: A structure and a method are provided for refilling a block of memory words stored in a cache memory. The structure and method provide a read buffer to optimally match the processor speed with the main memory using read clock enable RdCEn and acknowledge (Ack) signals. The RdCEn signal is provided as each memory word is available from the main memory. The Ack signal is provided to indicate the time at which the processor may empty the read buffer at the processor clock rate without subsequently executing a wait cycle to wait for any remaining memory words in the block to arrive. The benefit of the present invention is obtained without incurring a performance penalty on the single word read operation.

Abstract: A structure and a method provide data integrity for a multiprocessor system having a cache memory and a snoop tag cache. In one embodiment, the snoop tag cache copies the tags of a primary cache. Whenever a write operation occurs, the snoop tag cache is accessed to determine if the accessed tag matches a predetermined portion of the address of the memory location on which the write operation is performed. If so, a signal is sent to the CPU associated with the primary cache so that the corresponding entries in the primary cache and the snoop tag cache can be invalidated.

Abstract: A method and a structure provide a flexible cache module for use in cache memory performance modelling. The flexible cache module can be configured by jumper connections or switches into a cache memory having a line size and a cache size selectable from a number of combinations of line size and cache size. In addition, the flexible cache module can also be configured as either a split cache memory, for implementing separate data and instruction caches, or a unified cache memory.

Abstract: A structure and a method are provided to implement a memory bus arbiter, in which separate priorities are provided to instruction and data reads from the main memory. In one embodiment in a microprocessor with an on-chip cache, the present invention provides an arbiter which yields the memory bus, in decreasing priority order, to an ongoing bus transaction, a "direct memory access" (DMA) request, an instruction read resulting from a cache miss, a pending write request, and a read request, including reference to an uncacheable portion of memory and a data cache miss.

Abstract: In a microprocessor, two output pins are dedicated to providing information to assist in diagnosing problems relating to internal instruction and data caches or the software executing in the caches. The information on the pins is time-multiplexed. In a first phase, the pins indicate whether the data or instruction cache is accessed and whether a cache miss has occurred. In a second phase, the pins carry signals identifying the address reference which resulted in a cache miss.

Abstract: An integrated circuit dual port memory provides a preferred port which is always granted priority of memory access when memory access requests arrive simultaneous from both ports of the dual port memory. To implement this priority scheme, the memory request signal from the preferred port controls a multiplexor to select the input signals from the preferred port over the input signals from the non-preferred port. The memory request signal from the preferred port also serves as a busy signal to block a simultaneous memory access by the non-preferred port. In one embodiment, memory request signals of both ports are latched into registers clocked by the same clock signal.

Abstract: A multiplexed address and data bus system provides a minimum pin count with byte enable and burst address counter support. The partitioning of the address bus includes separate byte enables to indicate specifically which bytes of the word are being accessed, and two independent address lines which can function as a counter to support the burst refill. Both block reads or single datum transfers are handled similarly: a single addressing phase with multiple data phases; and all addresses in the memory system; are derived directly from the same pins regardless of whether it is a block read or not. The system allows for low cost packaging while maintaining a variety of system capabilities.

Abstract: A method of programming a cache tag comparator by designing a semiconductor device's internal circuitry such that an input/output pin of the device may be programmed by an external resistor to ground that will indicate during the reset phase of the device that an alternate function for the pin is to be selected or that the pin itself is to be disabled.

Abstract: An Ethernet controller, for use within an Ethernet network of other Ethernet controller connected together by a bus, is provided. The Ethernet controller includes a plurality of ports including at least one bus port associated with ports connected to other switching Ethernet controllers, a hash table for storing addresses of ports within the Ethernet network, a hash table address control, a storage buffer including a multiplicity of contiguous buffers in which to temporarily store said packet, an empty list including a multiplicity of single bit buffers, a packet storage manager, a packet transfer manager and a write-only bus communication unit. The hash table address control hashes the address of a packet to initial hash table location values, changes the hash table location values by a fixed jump amount if the address values stored in the initial hash table location do not match the received address, and provides at least an output port number of the port associated with the received address.

Abstract: An Ethernet controller, for use within an Ethernet network of other Ethernet controller connected together by a bus, is provided. The Ethernet controller includes a plurality of ports including at least one bus port associated with ports connected to other switching Ethernet controllers, a hash table for storing addresses of ports within the Ethernet network, a hash table address control, a storage buffer including a multiplicity of contiguous buffers in which to temporarily store said packet, an empty list including a multiplicity of single bit buffers, a packet storage manager, a packet transfer manager and a write-only bus communication unit. The hash table address control hashes the address of a packet to initial hash table location values, changes the hash table location values by a fixed jump amount if the address values stored in the initial hash table location do not match the received address, and provides at least an output port number of the port associated with the received address.

Abstract: A switched Ethernet controller (SEC) device and associated method that provides processor based intervention in the packet routing decision process is provided. The method of routing a multicast packet between a source port on a source device and a plurality of destination ports on a plurality of destination devices, utilizes a processor. The method includes the steps of the source device receiving the multicast packet via the source port, the source device sending the multicast packet to the processor, the processor examining the multicast packet, the processor determining the plurality of destination devices and corresponding the plurality of destination ports based on the results obtained during the step of examining, the processor transferring the multicast packet to the plurality of destination devices, and the plurality of destination devices sending the multicast packet to the plurality of destination ports.

Abstract: An Ethernet controller, for use within an Ethernet network of other Ethernet controller connected together by a bus, is provided. The Ethernet controller includes a plurality of ports including at least one bus port associated with ports connected to other switching Ethernet controllers, a hash table for storing addresses of ports within the Ethernet network, a hash table address control, a storage buffer including a multiplicity of contiguous buffers in which to temporarily store said packet, an empty list including a multiplicity of single bit buffers, a packet storage manager, a packet transfer manager and a write-only bus communication unit. The hash table address control hashes the address of a packet to initial hash table location values, changes the hash table location values by a fixed jump amount if the address values stored in the initial hash table location do not match the received address, and provides at least an output port number of the port associated with the received address.

Abstract: An Ethernet controller, for use within an Ethernet network of other Ethernet controller connected together by a bus, is provided. The Ethernet controller includes a plurality of ports including at least one bus port associated with ports connected to other switching Ethernet controllers, a hash table for storing addresses of ports within the Ethernet network, a hash table address control, a storage buffer including a multiplicity of contiguous buffers in which to temporarily store said packet, an empty list including a multiplicity of single bit buffers, a packet storage manager, a packet transfer manager and a write-only bus communication unit. The hash table address control hashes the address of a packet to initial hash table location values, changes the hash table location values by a fixed jump amount if the address values stored in the initial hash table location do not match the received address, and provides at least an output port number of the port associated with the received address.