Abstract: A memory management unit (MMU) is disclosed for managing a memory storing data arranged within a plurality of memory pages. The MMU includes a security check unit (SCU) receiving a linear generated during execution of a current instruction. The linear address has a corresponding physical address residing within a selected memory page. The SCU uses the linear address to access one or more security attribute data structures located in the memory to obtain a security attribute of the selected memory page. The SCU compares a numerical value conveyed by a security attribute of the current instruction to a numerical value conveyed by the security attribute of the selected memory page, and produces an output signal dependent upon a result of the comparison. The MMU accesses the selected memory page dependent upon the output signal. The security attribute of the selected memory page may include a security context identification (SCID) value indicating a security context level of the selected memory page.

Abstract: A programmable interrupt controller is provided for use in computer systems including one or more CPUs. The programmable interrupt controller includes an interrupt request interface, a storage device, and at least one processor interface having an interrupt nesting buffer. An interrupt request identification code is assigned to each interrupt request and stored in the nesting buffer. The interrupt request identification codes used to reference the interrupt requests are stored in order of their priority. Each nesting buffer need have only a number of entries equal to the number of priority levels.

Abstract: A multiprocessing computer system which includes an interrupt controller coupled to an expansion bus. The programmable interrupt controller has multiple storage locations at the same address for multiple CPUs. The CPUs are coupled to a host bus which in turn is coupled to the expansion bus by means of a bus bridge. An arbiter is coupled to the host bus for arbitrating bus mastership amongst the CPUs. CPU host owner identification for access to the storage locations is transferred across bus bridge to the programmable interrupt controller synchronized with the buffered address and data.

Abstract: A computer system employing an interrupt coprocessor is provided. The interrupt coprocessor is signaled by an interrupt controller to service a particular interrupt request. The interrupt coprocessor may include limited functionality, such that if a particular interrupt request is beyond the capabilities of the interrupt coprocessor, the microprocessor is interrupted. Context saves may be avoided in the interrupt coprocessor. Interrupt latency is reduced, as well as interruption of one or more main microprocessors in the computer system. Several embodiments are shown with a range of interrupt servicing capabilities. A data pump is shown, which is configured to transfer data from a source to a destination. A microcontroller is shown, which may manipulate the data as it is moved from source to destination or access the interrupting device to determine the service needed. Finally, a microprocessor similar to the main microprocessors of the computer system is shown.

Abstract: A symmetrical multiprocessing system is provided that includes a central interrupt control unit. The central interrupt control unit is coupled to a plurality of processing units and to a plurality of interrupt sources. The interrupt sources include a plurality of peripheral devices coupled to a first peripheral bus, such as a PCI bus. The interrupt sources also include devices coupled to a second peripheral bus, such as an ISA bus. The central interrupt control unit is operative in two modes. In a first mode, referred to as a pass through mode, interrupts from ISA peripheral devices are provided through an interrupt controller, such as cascaded type 8259 interrupt controllers, to the central interrupt control unit. The central interrupt control unit then passes the interrupt directly to a master processing unit. PCI interrupts are provided through a PCI mapper to other available interrupt inputs of the interrupt controller.