Unisys Corporation

Craig F Russ

Steven Clarke

Charles R Caldarale

Hans Christian Mikkelsen

Douglas E Morrissey

James R Hunter

Clark C Kogen

Sharon M Mauer

Stephen R Bartels

James C Prestifilippo

Maureen P Connell

Bruce Alan Vessey

Robert C Gulick

Eugene W Troxell

A method is disclosed for exchanging data between a central processing unit (CPU) and an input/output processor (IOP). The CPU and IOP may both be senders or receivers depending on whether data is flowing to or from the CPU. Where data is flowing to the CPU, the CPU is the receiver and the IOP is the sender. Where data is flowing from the CPU, the CPU is the sender and the IOP is the receiver. A sender evaluates the amount of empty buffers and, in a preferred embodiment, whether there is more data coming to determine whether to release partially full buffers in its buffer pool. Partially full buffers may be released based on any threshold as desired from a simple integer to a complex algorithm. The evaluation of whether to release partially full buffers is preferably implemented where a sender obtains at least one data packet for sending to a receiver and where a sender obtains an empty buffer from a receiver.

Method, system, for exchanging data via a buffer pool between a central processing unit and input/output processor that satisfies a predetermined threshold

Method and system for exchanging data between a central processing unit and an input/output processor

A stack frame associated with a procedure that can alter or affect a shared resource where the procedure is associated with a child stack and is declared by a parent stack is marked isolated. Isolated stack frames are allotted an additional predefined interval of processing time before commands such as terminate and interrupt applied to the child stack are executed. If the command is a terminate command, after the additional allotted time interval has passed, both child and parent stacks are terminated. If the command is an interrupt command, after the additional allotted time interval has passed, the child stack is interrupted. If the command is a resource-terminated command, an operator is permitted to allocate more resource time to the task or may terminate both parent and child stacks. If a parent stack is terminated, all child stacks of the parent are terminated.

Terminating a child process without risk of data corruption to a shared resource for subsequent processes

A file accessing scheme allows logical files to be processed outside of the native operating system and its logical I/O subsystem. When an application program wants to process a file outside of the native operating system, a file information block is built with a special type of file designated as 'virtual.' A pointer is provided within the file information block to a handler. The handler is a library that is external to the native operating system. The library processes the file without using the native operating system. Upon completion of the processing, the handler returns the operation results to the file information block and control is transferred back to the application program.

Virtual file system and method

A mechanism for managing pointers or handles to transient objects is disclosed. An anonymous token is assigned to an object. When an anonymous token is needed for an object, an unused token value is obtained from a list of available values and is associated with the object, the token value is removed from the list of available values, and data elements of a token data array entry associated with the anonymous token value are updated. When an operation is performed on an object identified by an anonymous token, data elements are evaluated and if reuse counts are not identical or if the validity indicator does not indicate that the object is valid, the operation is not performed. When an object is de-allocated, the token value associated with the object is returned to the available list and the data elements associated with the token value are updated.

System and method for using anonymous tokens for efficient memory management

A computer system comprises a plurality of processing modules that can be configured into different partitions within the computer system, and a main memory. Each partition operates under the control of a separate operating system. At least one shared memory window is defined within the main memory to which multiple partitions have shared access, and each partition may also be assigned an exclusive memory window. Program code executing on different partitions enables those partitions to communicate with each other through the shared memory window. Means are also provided for mapping the physical address space of the processors in each partition to the respective exclusive memory windows assigned to each partition, so that the exclusive memory windows assigned to each partition appear to the respective operating systems executing on those partitions as if they all start at the same base address.

Computer system and method for operating multiple operating systems in different partitions of the computer system and for allowing the different partitions to communicate with one another through shared memory

A plurality of buffers is provided which are shared in that each are capable of having data written to or from them by one or more user computer programs. Each of those buffers is dedicated to reading data from or writing data to a unique particular area in a storage device such as physical disk media. A first set of registers is provided for monitoring the status of each of a number of data transfers between any one of the user programs and a particular such storage location. A second set of registers is provided for monitoring the status of reads from a storage location, or writes to a storage location, via a particular one of the buffers. This system thereby keeps each user program informed of any read or write commands it has issued, while permitting a number of reads or writes between different user programs, and a single storage area served by a single shared buffer, to be accomplished in one input/output operation.

Method for reporting file write status in a shared file system

Method and apparatus for writing data to files from a computer system to a Write Once Read Many (WORM) Disc medium which results in a creation of an ISO 9660 standard disc is disclosed. The method and apparatus each efficiently manages writes to WORM medium in the creation of a file structure that conforms to ISO standard 9660 which governs management of CD-ROM disc files. The method and apparatus are efficient both in terms of the time required to perform such writes and in the amount of medium consumed as overhead. In addition, the invention provides a method and apparatus for writing to WORM disc in which there is a high degree of confidence that the information written is indelible.

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Berwyn, PA, United States of America

Craig F Russ