Abstract: One embodiment of a distributed memory module cache includes tag memory and associated logic implemented at the memory controller end of a memory channel. The memory controller is coupled to at least one memory module by way of a point-to-point interface. The data cache and associated logic are located in one or more buffer components on each of the memory modules.

Abstract: One embodiment of a distributed memory module cache includes tag memory and associated logic implemented at the memory controller end of a memory channel. The memory controller is coupled to at least one memory module by way of a point-to-point interface. The data cache and associated logic are located in one or more buffer components on each of the memory modules. Writes to a memory module are stored in the data cache which allows the writes to be postponed until the DRAM on the memory module is not busy.

Abstract: One embodiment of a distributed memory module cache includes tag memory and associated logic implemented at the memory controller end of a memory channel. The memory controller is coupled to at least one memory module by way of a point-to-point interface. The data cache and associated logic are located in one or more buffer components on each of the memory modules. The tag look-ups are performed in parallel with the memory module decodes. This improves latency for cache hits without penalizing the latency for cache misses.

Abstract: One embodiment of a distributed memory module cache includes tag memory and associated logic implemented at the memory controller end of a memory channel. The memory controller is coupled to at least one memory module by way of a point-to-point interface. The data cache and associated logic are located in one or more buffer components on each of the memory modules. One intended advantage of this example embodiment is the ability to read a current line of data out of a memory module DRAM and to load the next cache line of data into the memory module data cache. This allows the utilization of excess DRAM interconnect bandwidth while preserving limited memory bus bandwidth.

Abstract: One embodiment of a distributed memory module cache includes tag memory and associated logic implemented at the memory controller end of a memory channel. The memory controller is coupled to at least one memory module by way of a point-to-point interface. The data cache and associated logic are located in one or more buffer components on each of the memory modules. This embodiment includes an option to segment the cache. When the cache is segmented, the cache line size is halved. The segmentation allows the entire cache to be accessed without doubling the amount of tag address storage locations. The non-segmented cache may be used for memory systems using a burst length of eight bytes, while the segmented cache may be used for memory systems using a burst length of four bytes.

Abstract: A method and apparatus for powering down a memory device by deasserting a chip select line for a predetermined number of consecutive clock cycles and for powering up the memory device by asserting the chip select line.

Abstract: A method and apparatus for sequencing system bus grants and disabling a posting buffer in a bus bridge includes a bus activity monitor for monitoring bus cycles on a first bus, an inbound posting buffer, and a control logic. The control logic indicates whether to grant control of the first bus to a first processor on the first bus based on whether the inbound posting buffer is empty, and also controls disabling of posting to the inbound posting buffer. The control logic disables inbound posting responsive to both the first processor being backed off the system bus a predetermined number of times and the inbound posting buffer being empty.

Abstract: A hybrid decoding module which resides on the computer system's high speed memory bus. The computer system incorporating the hybrid decoding module scheme is capable of having centrally decoded resources on the memory bus as well as resources capable of decoding memory bus addresses directly. During system initialization, or after a hard reset, the decoding logic polls each of the resources on the memory bus to determine whether the resource is a centrally decoded resource or a distributed decode resource. A table is maintained for all centrally decoded resources such that when addresses are put out by the processor during run-time, the decoding logic is capable of directing control to the centrally decoded resource. Another aspect of the present invention is implemented during the initialization of the system. When resources are polled by the decoding logic, they are also provided with an identifier which identifies the last available I/O space slot.

Abstract: A hybrid decoding module which resides on the computer system's high speed memory bus. The computer system incorporating the hybrid decoding module scheme is capable of having centrally decoded resources on the memory bus as well as resources capable of decoding memory bus addresses directly. During system initialization, or after a hard reset, the decoding logic polls each of the resources on the memory bus to determine whether the resource is a centrally decoded resource or a distributed decode resource. A table is maintained for all centrally decoded resources such that when addresses are put out by the processor during run-time, the decoding logic is capable of directing control to the centrally decoded resource. Another aspect of the present invention is implemented during the initialization of the system. When resources are polled by the decoding logic, they are also provided with an identifier which identifies the last available I/O space slot.

Abstract: An asynchronous computer bus and method to maintain consistency of data contained in a cache and a memory which are each coupled to the bus. The bus comprises a cache hit indication means, a write access indication means, and a modified data indication means. A means is provided for invalidating a first portion of the cache, the invalidation means being operative upon activation of the cache hit indication means. Further, the bus comprises a modified data indication means and the write access indication means. A write-back means is provided for writing back the first portion of the cache data to the memory, the write back means being operative upon the first portion of the cache being invalidated by the invalidation means. Lastly, the bus comprises a shared data indication means which is operative on the cache hit indication means and upon failure of activation of the write access determination means.

Abstract: A hardware timer dedicated to the BIOS which operates independent of the CPU timer. The BIOS activates the timer by writing a delay count to a predetermined port. Address decode circuitry identifies an address match to a write port address. When an address match coincides with a write command from the BIOS, write control circuitry coupled to the address decode circuitry activates a "load" signal for loading the delay count into a counter circuit. The counter circuit, which is coupled to the write control circuitry, operates on a clock having frequency independent of the CPU operating frequency. The counter circuit comprises a flip-flop that synchronizes the "load" signal to the clock of the counter circuit. The synchronized "load" signal causes the delay count to be loaded into the counter circuit. The write control circuitry inactivates the "load" signal such that the delay count is loaded exactly once. The counter circuit counts when the synchronized "load" signal is inactive.