Abstract: The invention establishes the context in which data exchanged between dissimilar relational database management systems can be mutually understood and preserved, and data conversions can be minimized. The invention accomplishes this by establishing layers of descriptive information which isolate machine characteristics, levels of support software, and user data descriptions. Optimized processing is achieved by processing the different descriptor levels at different times during the development and execution of the database management systems. Minimal descriptive information is exchanged between the cooperating database management systems. Any data conversions that may be necessary are done only by the receiver of the data, and only at the point where it is necessary to have the data represented in the receiver's native format for processing.

Abstract: The invention provides transaction synchronization in the form of COMMIT processing in a distributed, heterogeneous database system wherein some resources are synchronized to a transaction by a single-phase commit procedures while other resources synchronize by multi-phase commit procedures. The invention invests an application requestor at an application site with authority to represent all single-phase commit resources in multi-phase commit processing.

Abstract: The invention establishes the context in which data exchanged between dissimilar relational database management systems can be mutually understood and preserved, and data conversions can be minimized. The invention accomplishes this by establishing layers of descriptive information which isolate machine characteristics, levels of support software, and user data descriptions. Optimized processing is achieved by processing the different descriptor levels at different times during the development and execution of the database management systems. Minimal descriptive information is exchanged between the cooperating database management systems. Any data conversions that may be necessary are done only by the receiver of the data, and only at the point where it is necessary to have the data represented in the receiver's native format for processing.

Abstract: Application programs which are developed and scheduled within a first computing system environment are permitted to access relational data registered at a remote database management system (DBMS) operating in a second computing environment dissimilar to the first computing environment. Access to data through the DBMS from an application execution site remote from the DBMS is supported by a process, logically subordinate to the application program which maps application program data access requests to the DBMS.

Abstract: A method for creating on-line presentations on a computer display using a complier, a compressor, and a processor. The complier converts control commands in source code format into object code format in order to specify how the information in an on-line presentation is to be presented on the display. The complier also creates a file identifying the image data to be used in the presentation. This file contains the names of the display units describing the image data used to indicate which of the uncompressed image data is to be operated upon by the compressor. The compressor formats and compresses the displayable picture elements of text and graphic shapes which have been used to create the on-line presentation. The processor then loads and executes the object code of the control commands with its corresponding picture elements of image data to create the on-line presentation. The control commands are generated totally separate from the image data.

Abstract: A method and apparatus are disclosed for enabling a diskette drive system to distinguish between diskettes and verify that the diskette currently in the drive is the correct one. Each diskette contains a file allocation table for controlling the allocation and deallocation of storage space on the diskette. Each time that the file allocation table on a diskette is accessed, i.e., read or written, a cyclic redundancy check (CRC) value for the file allocation table is calculated and stored. When checking the validity of a diskette, i.e., that the correct diskette is in the drive, a CRC value for the file allocation table of the currently loaded diskette is calculated and compared to the most recently stored CRC value. If the most recently calculated CRC value does not match the most recently stored CRC value, then this is an indication that the wrong diskette is currently in the diskette drive. A warning is then provided to the system user to change diskettes before a read or a write operation will be commenced.

Abstract: In a text processor including a communications facility, different tasks, such as typing tasks and communications tasks are entered into the machine from different program diskettes. As each is so entered, in view of the fact that main memory space is limited, it overlays control data in the main memory relating to the previous task. In a communications session, the operator has to build a queue of documents for sending under the control of communications foreground control (CFC) and communications background control (CBC) blocks in the main memory. If the operator is required to terminate this task before its completion, his queue data is lost as it is overlaid by control data relating to a new task that is entered, so on return to the communications task, he has to start from the beginning.

Abstract: A data communications system for asynchronous communication having at least two data transmit/receive terminals wherein the display is periodically updated with new send or receive data. In the receive mode the data is accumulated in a receive buffer for a predetermined time interval and then transferred into a text storage buffer which then activates a display access method to process the stored data and update the display. The display access method then goes into an "idle" mode and waits for the next transfer of data which does not occur until the predetermined time interval has expired. In the transmit mode the send data is transmitted without a delay but the display is updated after the predetermined time interval has expired.