Improved apparatus for specifying and computing the current length of varying-length data items, together with methods for computing the current length. The apparatus and methods are used in a digital computer system wherein data items are represented by names associated with name table entry items in memory. The name table entry associated with the name represented by the varying-length data item includes a current number of elements item specifier specifying the address of a current number of elements item which specifies the number of elements currently in the represented varying-length data item. The name table entry further includes an element size specifier specifying the size of the elements. A name processor in the processor uses the current number of elements item specifier to obtain the the address of the current number of elements item and and fetches the current number of elements item from memory. The name translator then calculates the current length using the element size and the current number of elements item.

In a database system having a dictionary/directory for collective management of definition information of the database system, when an application program is compiled to generate an object module, it is confirmed, by referring to the definition information stored in the dictionary, if a database access instruction in the application program is correctly operable. The confirmed definition information is incorporated within an object module which is edited to generate a load module. During execution of the load module, a database access control is effected using the definition information of the database system in the directory as well as the definition information incorporated at the compiling stage.

A digital computer system having a memory system organized into procedure and data objects, each having a unique identifier code and an access control list, for storing items of information and a processor for processing data in response to instructions. The instructions contain operation codes and names representing data. Each name corresponds to a name table entry in a name table which contains information from which the processor determines the location and the format for the data. The name table entry specifies a base address of one of a set thereof which change value only when a call or a return instruction is executed. A name interpretation system fetches a name table entry, calculates the base address and a displacement using the name table entry and the current architectural base address and adds the base address to the displacement to form the address of the data represented by the name.

A file directory structure and retrieval system for use in a computer that operates according to an operating system program and an application program. The memory of the computer stores files in a directory structure. A document locator module maps the directory structure of the files stored in the memory to a real world hierarchical file structure of files and directories. The mapping is independent of conventions of the operating system. The document locator module can create, move and delete files and directories without exiting the application program. An open module operates in the background of the application program and intercepts control of the processor when a command is executed to cause a file to be opened. The open module displays on the output device an open card to allow entry of information relating to the contents of the file and location of the file in the real world hierarchical file structure of the file. It causes the file to be opened. A save module operates in the background of the application program and intercepts control of the processor when a command is executed to cause the application program to request information about a file to be saved. The save module displays on the output device a save card to allow entry of information relating to the file. It also causes the file to be saved.

Apparatus for and method of searching a data base using variable search criteria. The data base consists of a set of files or portions thereof. Each file is divided into a number of records whereby all records of a given file have the same format but the records of different files may have different formats. A field format register is used to define the format of the records within a given file. The field format register specifies the location and width of each field within a record. To perform a search, a field-by-field comparison of each record is made to a reference word. The comparison yields a less than, equal to or greater than result for each field of each record. A field comparison register describes the expected result of the field-by-field comparison. A given field is designated true if the comparison yields the expected result specified for that field in the field comparison register. A given field is designated false if the comparison yields other than the expected result specified in the field comparison register. A hit on a given record is defined as satisfying a Boolean expression using the field-by-field true/false definitions as input variables. A given record is a miss if the Boolean expression is not satisfied.