A numerical control system equipped with a man-machine interface controller (MMC equipment) constructed in the form of a computer. The system comprises an NC unit (11), a programmable machine controller (13) which executes the sequence control relying upon the signals from the NC unit (11) and a machine tool (12), a man-machine interface controller (14) which is equipped at least with a CRT (14d) and a keyboard (14e) and which is constructed in the form of a computer, and a data transmission-reception control unit (15). The data are transmitted and received among the NC unit (11), the programmable machine controller (13) and the man-machine interface controller (14) while they are controlled by the data transmission-reception control unit (15).

Numerical control system

A conventional single node operating system is provided with a distributed file management system (DFS) with a plurality of nodes and a plurality of files. The DFS uses the UNIX operating system tree structure employing inodes (data structure containing administrative information for each file) to manage the local files and surrogate inodes (s -- inode) to manage access to files existing on another node. In addition, the DFS uses a lock table to manage the lock status of files. The method which implements the DFS locking of records and files involves the following steps. If the file is a local file, then the UNIX operating system standard file locking is used. However, if a remote file is to be locked, the UNIX operating system LOCKF and FCNTL system calls are intercepted and an remote process call (RPC) DFS -- LOCK -- CONTROL is executed. The server node receives the remote process call and carries out the lock request. The request could entail locking a single record, a set of records or the whole file. The server then acknowledges receipt of the RPC by sending a signal while the client surrogate inode is waiting for a reply from the DFS -- LOCK -- CONTROL RPC. The client confirms the reception of the lock and sends an acknowledgement to the remote server. The server updates the lock table after receiving the acknowledgement from the client surrogate inode. If the server does not confirm the reception of DFS -- LOCK -- CONTROL's acknowledgement, then DFS -- LOCK -- CONTROL updates the lock table.

System for file and record locking between nodes in a distributed data processing environment maintaining one copy of each file lock

Intelligent browsing through a collection of reusable software components is facilitated with a computer having a video monitor and a user input interface such as a keyboard or a mouse for transmitting user selections, by presenting a picture of encyclopedia volumes with respective visible labels referring to types of software, in accordance with a metaphor in which each volume includes a page having a list of general topics under the software type of the volume and pages having lists of software components for each one of the generic topics, altering the picture to open one of the volumes in response to an initial user selection specifying the one volume to display on the monitor a picture of the page thereof having the list of general topics and altering the picture to display the page thereof having a list of software components under one of the general topics in response to a next user selection specifying the one general topic, and then presenting a picture of a set of different informative plates depicting different types of information about one of the software components in response to a further user selection specifying the one component.

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Encyclopedia of software components

In the maintenance of a stored relational database, signals representing record occurrences related to a record occurrence of a starting relation are retrieved. Stored relationship attribute signals, including specification of a common relationship field, are used to generate a generic cursor defined against the destination relation record occurence is selected, values of the specified relation; the generic cursor is stored, and when a starting field are copied from it to the generic cursor to form a completed cursor. Destination relation record occurrence signals defined by the completed cursor are accessed and stored. Retrieval can be carried out interactively, allowing an operator to select from a display the starting relation record occurrence and the operation of retrieving the related occurrences, and to view representations of the stored destination record occurrences.

Retrieval of related records from a relational database

A method of assuring that each of a plurality of contemporaneously active database transactions comprising at least one read transaction and at most one update transaction has a consistent view of a database storing a plurality of versions of a relation. A transaction has a consistent view of a database if the data available to a transaction are not changed during its execution. An access dictionary is stored comprising an array of access blocks each defining the database location of one of the relation versions. At any given time, only one of the relation versions is defined as current. A relation dictionary comprising an array of relation blocks is stored such that as each database transaction is begun, a relation block associated with that database transaction is stored defining the access block defining the database location of the relation version then defined as current. For the update transaction, a new access block in the access dictionary is stored defining a new database location to be used for storing a new relation version. The relation block associated with the update transaction is modified to define the new access block and the new relation version is stored in the new database location. In addition the current relation version is redefined as old and the new relation version is defined as current. Access to the database by each of the plurality of database transactions is permitted only via the relation block associated with that database transaction. The method can be extended to allow contemporaneous access by noninterfering writers and an arbitrary number of readers to a database storing a plurality of relations each having a plurality of versions.

Database management system for controlling concurrent access to a database

Data access in a data base management system is controlled. The method for controlling the data access in a computer having a first memory and a sub memory, both for storing data required to execute a program, including at least one data operation instruction comprises the steps of transferring data required by the data operation instruction from the sub memory to a location in the first memory, prior to execution of the data operation instruction, and informing the data operation instruction of the address of the location of the data required thereby, prior to execution of the data operation instruction. The apparatus for controlling data access comprises a sub memory for storing a data base and programs including at least one task unit having at least one data operation instruction, a first processor for executing each task unit stored in the sub memory, a first memory for storing programs and data executed by the first processor, a second processor connected to the sub memory, and a second memory for storing programs and data executed by the second processor, whereby the first processor executes the task unit read out from the sub memory, while the second processor reads out the data from the sub memory specified by the data operation instruction included in the task unit, based on the parameter supplied from the first processor and stores the data read out from the sub memory and corresponding addresses in the first memory.

Ken Masegi

Papers

Method and apparatus for controlling a data access in a data base management system

Verfahren zur steuerung des datenzugriffs in einem rechner und daten-kontrollsystem zur durchfuehrung des verfahrens