Abstract: A write-once read-many (WORM) optical disk recorder automatically calibrates its laser to emit a laser beam of a desired power level. While writing data to the WORM disk, a laser test signal is written to a laser checking area termed Automatic Laser Power Correction (ALPC) field. If the emitted laser test signal has a power level outside an acceptable power level window, then inappropriate laser power is indicated. Then, in an error recovery procedure (ERP) the laser power is calibrated in the data sector to be written to using short spaced-apart laser test signals. After successful calibration, data are written to the sector. The test signals appear as burst errors that can be corrected by a suitable error correction code. If such calibration is not successful then a write calibrate sector, WCS, is created and used for an extensive automatic calibration. In the WCS both laser power level is calibrated. The calibration result information is written to WCS for later use.

Abstract: Fault tolerance in a redundant array of disk drives is degraded when error conditions exist in the array. Several methods for rebuilding data of the array to remove the degradation are described. Data rebuilding for entire disk drives and partial data rebuilds of disk drives are described. All rebuild methods tend to reduce the negative affect of using array resources for the data rebuild. In one method rebuilding occurs during idle time of the array. In a second method rebuilding is interleaved between current data area accessing operations of the array at a rate which is inversely proportional to activity level of the array. In a third method, the data are rebuilt when a data area being accessed is a data area needing rebuilding.

Abstract: A pipeline data processor is simultaneously operable in a pipeline mode, a parallel mode and a vector mode which is a special case of the pipeline mode. Each pipeline stage has its own stage program counter. A global program counter is incremented in the pipeline mode. The instruction addresses generated in the global program counter are distributed to those pipeline stages which first become available to perform pipelined data processing. Any given pipeline stage may dynamically switch between pipeline mode and a parallel mode in which the stage program counter counts and supplies instruction addresses independently of any other pipeline stage. A vector mode uses pipeline instructions which are repeated to enable any number of the pipeline stages to participate in vector calculations. In the vector mode, one pipeline instruction address is held in the global program counter to be repeatedly supplied to respective first available pipeline stages until the vector calculations are completed.

Abstract: One or more data-storing disk devices support logical tracks extending between radial recording zones of tracks in the device(s). Each data-storing disk in the device(s) is formatted into a plurality of radial recording zones of physical tracks, each radial recording zone having a like number of physical tracks, each physical track may be one circumvolution of a single spiral track. The physical tracks in the respective recording zones store a different number of data bytes. Each logical track including a plurality of said physical tracks; at least one of the physical tracks in each of the logical tracks is in a different one of the radial recording zones in different ones of the devices or in a single device. Described are an extended logical track and extended logical cylinder accessing methods and apparatus. Not all of the physical tracks of any of the devices or recording zones need be a member of any logical track.

Abstract: An APL environment includes the usual workspaces plus so-called packaged workspaces. The disclosed packaged workspaces are load modules created from saved workspaces. An active APL workspace can access a loaded copy of the packaged workspaces using external names of named objects in a packaged workspace rather than internal names of its own named objects. Program execution associated with the packaged workspaces is controlled through a copy of the packaged workspace name table stored in the active workspace accessing the read only packaged workspace. Access to packaged workspaces not only can be concatenated from other packaged workspaces, but also can be shared among a plurality of active workspaces.

Abstract: A state of operation is established in accordance with rules for a peripheral subsystem which enables reduced channel time for executing ensuing related channel commands of the same channel program. In a peripheral data-storage subsystem, a set of rules of operation are established. Each rule sets forth a predetermined set of sequences of channel commands during any chain of channel commands (channel program) which predict ensuing channel operations in channel program currently being executed. Once any rule is satisfied, a state of operation is established in the subsystem for responding to ensuing channel commands in the same channel program and which relate to the channel commands set forth in the rules. So long as such related ensuing channel commands continue or until the end of the channel program the state of operation is maintained in the subsystem.

Abstract: In a programmed machine, such as an peripheral controller, programmed operations are executed in a one of several operational contexts. Each context may be initiated by a corresponding interruption signal. Any context which has been activated remains active until quiesced by program execution. One of the active contexts is a current context in which all instruction executions are currently occurring. In each cycle of the programmed machine, all active contexts and received and stored interruption signals, each for respective ones of the contexts, are compared to find the context highest priority context. Such highest priority context is compared with the current context priority for determining whether or not the programmed machine should change current contexts.

Abstract: Units of data (data sets, data bases, etc.) are allocated data storage space in a data storage system based on implicit analysis of the unit of data. A plurality of data classes, each defining predetermined characterisitics of diverse units of data, are established for the data storage system. A plurality of storage classes, each defining predetermined sets of storage performance and availability requirements are established for the data storage system. A plurality of management classes, each defining respective diverse sets of life cycle attributes for units of data are established for the data storage system. A plurality of storage groups, each defining diverse predetermined performance device and management available in the data storage system but independently of the individual storage devices of the data storage system are established. The devices are selectively assigned to different ones of the established storage groups.

Abstract: An access control or arbitrator for a shared resource, such as a time-slotted bus, groups requests according to priorities of the requests. The time slots are grouped into sets, each set having a number of successive time slots equal to the number of sources supplying access requests having a highest priority. In a highest priority group, each source supplying a highest priority access request is guaranteed access in respective ones of said time slots in each set of time slots. When any time slot is not being used by a high priority request, low priority requests then have access to the unused time slot. Lower priority groups of access requests are handled in accordance with a different algorithm, such as a round robin priority algorithm.

Abstract: A pattern-matching network is merged with an existing RETE network without recompiling the whole network, while still matching existing data. Permanent, temporary, full and partial merging operations are described, depending on the origination of match patterns among LHS, on demand (procedural programming), or top level. The merge process combines functionally identical nodes from the networks for reducing the number of nodes in the resulting network. The merger process produces so-called alpha and beta synapse nodes; alpha synapse nodes have pointers to top nodes, while beta synapse nodes consist pointers to a drain node, which is a node in the grafted RETE portions of the resulting network and to source memory nodes in the pre-existing RETE network. The algorithm for obtaining a set of synapse nodes without duplication of any logic connecting paths is described. The synapse nodes are used in updating a grafted network, also can be a suspended portion, upon completion of the merger.

Abstract: A pattern-matching system, such as of the RETE type, is updated. The updating operation is generalize to operate with correct match resuslts for generalized RETE networks (ones where join nodes may have either predecessor be another join node), and for arbitrary partial update state, characterized by stop nodes designating how far update operations have progressed for particular update tokens (designated suspended tokens) at any particular time. The updating operation consists of the following steps: First, all tokens only partially updated through the network are shadowed, in that the partial result memories associated with the stop nodes are put into the state that exists or existed before the suspended tokens arrive at the stop nodes. Then for each suspended token, it is pushed to resume nodes connected as RHS (or LHS) inputs in a descending order of resume nodes.

Abstract: APL, an interpretive processor, cooperates with external routines by calling those external routines to process data passed to them and receives results from the external routines. The called external routines, during their respective execution of the call, can request internal services of the calling APL interpretive processor. Such requests include execution of internal APL functions or operators, calling other external routines, recursive execution of external routines, and setting or obtaining values of internal APL data items.