Abstract: The pipelined central processing system (CSS) units of a multiprocessor system are tightly coupled to connect in common to a system bus for sharing main memory and input/output controllers/devices. The CSS includes several circuit boards for the different VLSI circuit chip pipelined stages and associated control circuits in addition to the bus interface unit (BIU) circuits. Each board includes one or more unusual event (UEV) detector circuits for signaling when the behavior of a stage is abnormal. The UEV fault signals from each board are collected by the BIU board. When a UEV fault is detected, the BIU board circuits prevent any further communications with the system bus and broadcasts the UEV fault signal to the other boards causing the different pipelined stages to emulate the completion of the instructions within the pipeline thereby flushing it. It is thereafter placed in a nonpipelined mode.

Abstract: A multiprocessor system includes a plurality of identical central subsystem (CSS) units, a plurality of memory and input/output (I/O) subsystem units which connect in common to an asynchronous bus system. Each CSS subsystem unit includes a cancel command mechanism for enabling each such unit to effectively withdraw from the asynchronous bus or switch the state of a resource such as a memory or I/O lock mechanism included in such subsystem without otherwise disturbing the state of such subsystems.

Abstract: An adapter is connected between a peripheral controller and an intelligent peripheral device. The adapter allows the peripheral device to communicate with the controller. The adapter has control logic rather than a microprocessor for transmitting and receiving data. The control logic is comprised of combinatorial logic circuitry and a command register. The command register allows the controller to configure the cominatorial logic circuitry in order to control adapter operation.

Abstract: A multiprocessor system includes a system management facility (SMF) unit, a plurality of central subsystem (CSS) units, a plurality of memory subsystem units and first and second pluralities of input/output units which connect in common to a system bus. Requests are transferred between a pair of units on a distributed bus priority network included as part of the system bus on the basis of the unit's physical position on the bus relative to one end of the bus. The SMF unit positioned at the high priority end of the bus includes fast recovery bus request logic circuits which connect to the high priority request line of the priority network. Each of the CSS units positioned after the SMF unit on either side of the memory subsystems includes bus request logic circuits which connect only to the low priority request line. The memory subsystems each include bus request logic circuits which connect to both the high and low priority request lines for accepting and granting cycles from higher and lower priority units.

Abstract: A pipelined processing unit which includes an instruction unit stage containing logic management apparatus for processing a set of complex instructions. The logic management apparatus includes state control circuits which produce a series or sequence of control states used in tracking the different types of instructions of the complex instruction set being processed. Different ones of the states are used for different types of instructions so as to enable the different pipeline stages to operate both independently and jointly to complete the execution of different instructions of the complex instruction set.

Abstract: In a data processing system having a plurality of tightly coupled data processing units connected by an asynchronous system bus, apparatus and an associated method are described for maintaining the coherency of data groups stored in instruction cache units and execution cache units. The apparatus includes a monitor unit as part of the bus interface unit, and a bus interface unit coupling each associated data processing unit to the system bus. The monitor unit receives signals, applied to the system bus, identifying data groups transferred between the memory unit and the data processing units, including those data groups originating from the bus interface unit of which the monitor unit is a component. The bus interface unit includes directories duplicating the contents of the instruction cache unit directory and the execution cache unit directory.

Abstract: A memory system containing groups of random access memory (RAM) devices further includes apparatus for distributing input memory addresses so diffused so as to cause the selection of different relative physical cell locations within each RAM device being accessed to provide a single word of information.

Abstract: A virtual memory management cache memory system has a plurality of directory and buffer store levels for storing page descriptor information. The cache memory directories and a least recently used (LRU) apparatus for replacing information within the buffer store on a least recently used basis are constructed from the same type of standard cache address directory part. Programmable control circuits generate the required input data and control signals which are applied to the LRU apparatus for obtaining signals which indicate a next level to be replaced on a least recently used basis and for updating the contents of the LRU apparatus on a most recently used basis.

Abstract: In a data processing system in which each of the data processing units is implemented using pipeline techniques and has a cache memory unit employing a store through strategy, the time required to prepare a write instruction operand address can be substantially shorter than the time required by the execution unit to prepare the associated write instruction operand. In order to utilize the time difference, apparatus is included in the execution cache unit for storing the write instruction operand address during the preparation of the associated write instruction operand. After storing the write instruction operand address, a next address is entered in an input register of the execution cache unit. When the newly entered address is associated with a read instruction, does not conflict with the write instruction operand address, and produces a "hit" signal when applied to the execution cache unit tag directory, the read instruction is processed by the execution unit.

Abstract: A system provides for the testing of components which connect to one or more of programmable logic devices (PLDs), each of which is organized in a predetermined manner. Each PLD includes a plurality of programmable logic sections, each of which connect to I/O pins through driver and receiver circuits. An available section includes programmed means for causing its driver circuit to force the I/O pin to a first logic level when made operational. The other sections each include programmed means for connecting their associated driver circuits to be controlled by signals applied to the receiver circuit of the available section. During testing, means are externally applied to the I/O pin of the available section which drive the pin from the first logic level to a second logic level.

Abstract: A system for automating the dump analysis process includes a remotely located host computer system which, in response to requests from a local expert computer system, retrieves only relevant values from one or more physical memory dumps. The expert system reconstructs from these values the operating system control structures represented in the dump, and applies expert knowledge on these control structures to determine the symptom of the problem occurring on the computer system which stopped operating and generated the dump.

Abstract: A peripheral device controller has an EEPROM which stores microinstructions to be placed in a random access memory control store. The EEPROM also stores peripheral configuration information. This information is obtained by polling the peripheral devices connected to the controller and storing the resulting information in the EEPROM. Upon powering up, the microinstructions stored in the EEPROM are transferred to the control store via execution of instructions held in a boot PROM. The controller, therefore, provides a fast control store while maintaining permanence of the microinstructions after power is extinguished. Means are also provided to update the control store and EEPROM. The EEPROM may upon CPU command be updated with new microinstructions held in main memory or obtained from peripheral devices.

Abstract: A computer memory interpretation file, or structures file, enables automatic location and interpretation of memory resident components of operating system programs, user programs, data buffers, and the like. The structures file contains sufficient information pertaining to each control structure to allow a program using it to identify and locate each iteration of any component that may be memory resident. The structures file relieves the program of requiring reference definitions pertaining to the control structures or their sub-components and eliminates the requirement for programming logic normally necessary to recognize and perform specialized operations determined by the nature of the control structure being processed.

Abstract: A plurality of units which are coupled to transfer requests, transfer data over an asynchronous bus network during allocated bus transfer cycles. The network has a tie-breaking bus priority network which is distributed to a common interface portion of each of the plurality of units and grants bus cycles and resolves simultaneous requests on a priority basis. At least one unit includes bus saturation detection apparatus included within its common interface portion for monitoring bus activity over established intervals of time. The detection of the occurrence of at least one available cycle over the given interval of time signals that the bus network is not in a saturated state. When the indicator specifies that the bus network is saturated, the unit throttles down its operation by increasing the amount of time between issuing data requests. Throttling continues until the bus is no longer being saturated.

Abstract: A controller connected between a system bus and peripheral devices has at least two microprocessors. One controls the data transfers with the peripheral devices, and the other controls data transfers with the system bus. The microprocessors share a data buffer and control store. This sharing is possible because of the controller timing means which synchronizes exclusive access to the shared components of the controller. When first initialized, the microprocessors are directed to execute a test instruction which points them to the beginning of their set of microinstructions. Once pointed to their set of microinstructions, normal operation may begin.

Abstract: A pipelined processing unit includes an instruction unit stage containing resource conflict apparatus for detecting and resolving conflicts in the use of register and indicator resources during the different phases of instruction execution. The instruction unit includes a plurality of resource registers corresponding in number to the number of instructions which can be processed concurrently by the processing unit. Decode circuits in response to each new instruction received by the instruction unit generate one or more sets of bit indication signals designating those resources required by the specific pipeline stage(s) executing the instruction for completing the execution of the instruction which are shared by those stages capable of completing the execution of instructions.

Abstract: A timing generator module is constructed from a single multitap active delay line circuit. The delay line taps are customized to delay an input pulse by different amounts, the differences between the amounts being selected as a function of the widths of the output pulses to be generated by the module. The output pulses from each of a number of different pairs of taps are logically combined within corresponding ones of a number of output logic gate circuits. A selected one of each pair of pulses is inverted before being logically combined with the other pulse of the pair for accurately controlling the transitions of the corresponding output pulse. The active delay line circuits are packaged within a single dual line package for maintaining accurate tolerances.

Abstract: In a digital computer system in which arithmetic operands are addressed in instructions by their most significant digits, and in which operands need not start or end on particulr boundaries in system memory, apparatus is provided for calculating information from data available during instruction decoding and for using that information during operand fetching to fetch operands least significant digit first, and to store them in a scratchpad memory right-justified on double-word boundaries and filled with leading zeros.

Abstract: A segment descriptor unit (SDU) includes a divided random access memory (RAM), a content addressable memory (CAM) and decoder circuits interconnected for performing dynamic and static address translation operations within a minimum of chip area and power. The CAM is arranged to store a number of entries which include segment number and validity information associated with a corresponding number of segment descriptors. The RAM contains locations allocated for storing segment descriptor words (SDW's) and working data. Each SDW is logically divided into two fields, a static translation word (STW) field containing all of the bits required for performing a static address translation operation and an access control word (ACW) field containing all of the bits required for verifying compliance with system security. The bits of each STW and ACW are stored in alternate bit positions of the SDW locations. Each pair of RAM bit locations couple to a common read/write amplifier and multiplexer circuit.

Abstract: In a data processing system in which the execution unit is implemented to process aligned double word operands, apparatus and an associated method provide for the alingment of a double word operand that is stored across a double work boundary. The two double words each storing a word of the unaligned double word operand are identified and the attributes are compared with the ring number of the associated program. When the comparisons indicate that the two words of the non-aligned double word operand are available to the program, the two double word operands containing the non-aligned words of the double word operand, and the two non-aligned words are stored in a register in an aligned orientation for processing by the execution unit.