Abstract: According to the present invention, a pipelined SRAM structure and clocking method is disclosed. The SRAM interface and clocking method are specifically intended for use with Level 2 and Level 3 cache SRAM memory devices. In the present invention, the oscillator that generates the clock signal for the CPU is also used to generate the clock signals for all of the other components that interface with the SRAM. Each of the generated clock signals are dependant on the same clock event, allowing the clock speed to be decreased for testing or debugging while maintaining higher speed clock edge relationships. The various clock signals that are generated from the oscillator are used to cycle-steal time from multiple cycles. This technique allows sub-5 nanosecond (nS) access to Level 2 and Level 3 cache memory devices that have access times greater than 5 nS.

Abstract: A hierarchical memory utilizes a translation lookaside buffer for rapid recovery of virtual to real address mappings and a cache system. Lines in the cache are identified in the cache directory by pointers to entries in the translation lookaside buffer. This eliminates redundant listings of the virtual and real addresses for the cache line from the cache directory allowing the directory to be small in size. Upon a memory access by a processing unit, a cache hash address is generated to access a translation lookaside buffer entry allowing comparison of the address stored in the TLB entry with the address of the memory access. Congruence implies a hit. Concurrently, the cache hash address indicates a pointer from the cache directory. The pointer should correspond to the cache hash address to indicate a cache directory hit. Where both occur a cache hit has occurred.

Abstract: A shared bus non-sequential data ordering method and apparatus are provided. A maximum bus width value and a minimum transfer value are identified. A minimum number of sub-transfers is identified responsive to the identified maximum bus width value and the minimum transfer value. A bus unit having a maximum number of chips to receive and/or send data receives data in a predefined order during multiple sub-transfers. During each data sub-transfer, a corresponding predefined word is transferred to each chip of the bus unit.

Abstract: The ability to harmonize the activities of individual computer system components with control signals is key to the operation of any computer system. Examples of this need for control include the need to write data to multiple registers on the same clock cycle, the need to clear values on multiple entities on the same clock cycle, and the need to stop and start the master clock pulse train itself. In the past, providing this control was not a problem because control signals could be reliably sent to all the timing dependent components within a single cycle of the master clock pulse train. This control methodology is called "single cycle control." Today, however, single cycle control is not trustworthy in all situations. Master clock pulse trains are so fast that single cycle control is no longer reliable when timing dependent components reside in locations distant from the control signal generating circuitry.