Abstract: A data processing system includes at least one processor and data storage containing an array including N records having value-ordered entries. To find an entry matching a search value, W, a number of records to be searched, is set equal to N, and each of the W records is assigned to either a first set or a second set, where the first set includes X/2 of the W records and X is a smallest power of 2 equal to or greater than W. In response to a determination that the search value precedes the first record within the second set, a binary search of the first set of records is performed to identify a record including an matching entry. If the first entry of the first record within the second set matches the search value, the first record within the second set is identified.

Abstract: A method and data processing system for emulating a program are disclosed. According to the present invention, the data processing system runs under a first operating system and emulates the execution of a program under a second operating system within a second data processing system. The data processing system includes a memory which stores at least a portion of the first operating system and an emulator comprising a plurality of routines which each emulate an instruction utilized by the first operating system. The memory further includes a simulated mass storage data area which stores at least a portion of the program and a simulated main memory data area. The data processing system further includes a processor which executes instructions within the program under the first operating system by emulation. According to the present invention, the emulator accesses instructions of the program directly from the simulated mass storage data area to minimize emulation overhead.

Abstract: A method and data processing system for emulating a program are disclosed. According to the present invention, the data processing system runs under a first operating system and emulates the execution of a program under a second operating system within a second data processing system. The data processing system includes a memory which stores at least a portion of the first operating system and an emulator comprising a plurality of routines which each emulate an instruction utilized by the first operating system. The memory further includes a simulated mass storage data area which stores at least a portion of the program and a simulated main memory data area. The data processing system further includes a processor which executes instructions within the program under the first operating system by emulation. According to the present invention, the emulator accesses instructions of the program directly from the simulated mass storage data area to minimize emulation overhead.

Abstract: A computer system and method for efficiently managing Write Once Read Mostly (WORM) volumes on mass optical storage devices are disclosed. A configuration menu asks the user to enter a threshold percentage from 1-100%. The threshold percentage is multiplied by the volume size to determine a threshold block address. New files are written sequentially to the WORM volume up to but not exceeding the threshold block address, unless a threshold override indicator is enabled. Space on the WORM volume between the threshold block address and the end of the WORM volume is reserved for updated files. Updated files can be stored anywhere on the WORM volume, including above the threshold block address. Reserving space for updated files on a WORM volume allows more updated files to be stored on the same WORM volume as original files, and reduces the number of optical disks required to be read.

Abstract: A method of and apparatus for automatically assigning a name to a storage file. This assignment technique is particularly pertinent to storage files used in conjunction with an optical storage system. The automatically assigned name is used throughout the system to identify the storage file for all purposes including loading and unloading the storage file to and from the various drives within the system, initializing the storage file for use, and reading and writing to and from the storage file. Automatic name assignment normally occurs when a storage file is placed within a mass storage library. A name becomes necessary at that time because the storage file is then available to the system. Alternate automatic name assignment also occurs when for any reason the system is unable to read the name written on a storage file. The automatically asigned name may be replaced with a user supplied name upon operator request.

Abstract: In a processor having a real address space larger than its virtual address space, all of the physical memory is addressed by using a separate prefix register associated with each of the address registers to hold both a high-order address portion and a control bit specifying whether the address is to be translated or used as a direct real address.