Abstract: A computer system includes a central processing unit and a memory management unit having a plurality of functional units, such as a memory interface unit, a remote interface unit, a cache interface unit, and a translation unit. Each functional unit has a low priority error queue for storing error information for errors having a low priority. Some functional units also have a high priority error queue for storing error information for errors having a high priority error. Based on the status of the error queues, the memory management unit prioritizes and handles errors caused by hardware failures. For low priority errors, an interrupt request signal is sent to the central processing unit. For high priority errors, a RED ALERT signal is sent to the processing unit to cause the processing unit to give immediate attention to the error. For high priority error queue overflows, a failure signal is generated which causes the system to be halted and the contents of the system to be scanned out.

Abstract: A method and apparatus for performing address translation in a computer system supporting virtual memory by searching a translation lookaside buffer (TLB) and, possibly, a translation table held in memory and implemented as a B-tree data structure. The TLB is initially searched for a translation for a specified input address. If exactly one valid entry of the TLB stores a translation for the specified input address then the output address corresponding to the specified input address is determined from the contents of that entry. Otherwise, the translation table is searched for a translation for the specified input address. If two or more valid entries of the TLB store a translation for the specified input address then these entries are invalidated.

Abstract: A memory management unit (MMU) includes a translation lookaside buffer capable of simultaneously servicing three requests supplied to the MMU by an instruction cache and two data caches, respectively. Also, an arbiter selects one of several pending requests from sources of different priorities for immediate processing by the MMU, using a process which avoids undue delay in servicing requests from sources of lower priority.

Abstract: A method and apparatus for performing address translation in a computer system supporting virtual memory by searching a translation lookaside buffer (TLB) and, possibly, a translation table held in memory and implemented as a B-tree data structure. The TLB is initially searched for a translation for a specified input address. If exactly one valid entry of the TLB stores a translation for the specified input address then the output address corresponding to the specified input address is determined from the contents of that entry. Otherwise, the translation table is searched for a translation for the specified input address. If two or more valid entries of the TLB store a translation for the specified input address, then these entries are invalidated.