File update programs, such as the UNIX make command are invaluable, but enigmatic. They are difficult to write because the repercussions of an algorithmic variation can be elusive. Even experienced users often specify...
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File update programs, such as the UNIX make command are invaluable, but enigmatic. They are difficult to write because the repercussions of an algorithmic variation can be elusive. Even experienced users often specify file relationships incorrectly, and are occasionally surprised by the tool's behavior. This paper develops a rigorous conceptual model and employs it to answer some of the questions facing writers and users of file update tools. Coupled with empirical data about makefiles, these results motivate a conceptually simple update program.
In using Apple's professional Disk Operating System (ProDOS) as files are added to and deleted from a disk its directory becomes filled with file-name entries that the Catalog command displays in a chaotic order. ...
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In using Apple's professional Disk Operating System (ProDOS) as files are added to and deleted from a disk its directory becomes filled with file-name entries that the Catalog command displays in a chaotic order. This is because ProDOS directories are simply built sequentially - the operating system does not sort by file-name. A program is described that is designed to eliminate long catalog searches by sorting the valid file-names in the volume and subordinate directories of the ProDOS disk. It also permanently stores the sorted file-names on the disk so that an alphabetically sorted directory is displayed each time you request a catalog.
In programming beacons are lines of code which serve as typical indicators of a particular structure or operation. This research sought evidence for the existence and use of beacons in comprehension of a sort program....
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In programming beacons are lines of code which serve as typical indicators of a particular structure or operation. This research sought evidence for the existence and use of beacons in comprehension of a sort program. In the first experiment, subjects memorized and later recalled the whole sort program. Experienced programmers, but not novices or intermediates, recalled the beacon lines much better than non-beacon lines. In the second experiment, experienced programmers studied the same program and then were asked to recall several isolated parts of it. They did not know in advance that they would be asked to recall. Subjects recalled the beacon much better than non-beacon parts. They also were more certain that they recalled the beacon correctly. The results of both experiments support the idea that beacons exist as a focal point for study and understanding of programs by experienced programmers.
A software-development environment is a collection of software parts (often, but not always associated with a specific operating system and language) that aids in the conception, design, development, production, maint...
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A software-development environment is a collection of software parts (often, but not always associated with a specific operating system and language) that aids in the conception, design, development, production, maintenance and revision of programs. This article introduces six major software-development environments (Ada, Forth, Lisp, Prolog, Smalltalk and Unix), and shows how the increasing demand for cost-effectiveness in software development has made the adoption of a computer system's software-development environment a major design decision.
Emerald is an object-based language for the construction of distributed applications. The principal features of Emerald lnehtde a uniform object model appropriate for programming both private local objects and shared ...
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In this brief paper we propose a simple scheme to extract implicit parallelism in the low-level match phase of the parallel execution of Production System programs. The essence of the approach is to replicate rules wh...
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ISBN:
(纸本)0444879870
In this brief paper we propose a simple scheme to extract implicit parallelism in the low-level match phase of the parallel execution of Production System programs. The essence of the approach is to replicate rules while introducing new constraints within each copy to restrict each individual rule to match a potentially smaller set of data elements. Speed up is achieved by matching each copy of a rule in parallel. Variations of this approach may be applicable to logic-based programmingsystems, such as PROLOG, executed in a parallel environment. Indeed, sequential implementations of OPS-style production systems based on the Rete match algorithm may enjoy performance advantages as well. This scheme may be implemented by a simple preprocessing stage which requires no modification to the underlying match algorithms.
A fundamental measure of processing power in a database management system is the performance of the sort utility it provides. When sorting a large data file on a serial computer, performance is limited by factors invo...
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ISBN:
(纸本)0818607246
A fundamental measure of processing power in a database management system is the performance of the sort utility it provides. When sorting a large data file on a serial computer, performance is limited by factors involving processor speed, memory capacity, and I/O bandwidth. An investigation is made of the feasibility and efficiency of a parallel sort-merge algorithm through implementation on the JASMIN prototype, a backend multiprocessor built around a fast packet bus. The design and implementation of a parallel sort utility are described. The results of measurements corresponding to a range of file sizes and processor configurations are analyzed, showing that using current, off-the-shelf technology coupled with a streamlined distributed operating system, three- and five-microprocessor configurations provide a very cost-effective sort of large files. The three-processor configuration sorts a 100-Mb file in one hour, which compares well with commercial sort packages available on high-performance mainframes.
A construct called a mediator is described. Mediators support synchronization and scheduling for systemsprogramming within distributed systems. Mediators are based on a resource view of systems, and fit within a prog...
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ISBN:
(纸本)0818606975
A construct called a mediator is described. Mediators support synchronization and scheduling for systemsprogramming within distributed systems. Mediators are based on a resource view of systems, and fit within a programming methodology that emphasizes resource modularity, synchronization modularity and encapsulated concurrency. The authors examine other existing synchronization mechanisms in the light of modular programming requirements. A sample syntax and semantics for mediators is presented with many examples. The mediator includes many interesting features. These include: an adaptation of guarded commands;keys that allow requests to be examined and manipulated before they receive service;parallel guard execution;and coupled and uncoupled modes of service execution.
A library containing in excess of 280 standard cells was created in 9 months with only five people. This was accomplished using a compilation approach to generate layouts and simulation models for standard cells. A mo...
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A library containing in excess of 280 standard cells was created in 9 months with only five people. This was accomplished using a compilation approach to generate layouts and simulation models for standard cells. A modular approach was used to speed up characterization and documentation of the library.
TOOLS, a disk and conference manager, is an experimental system that lets files on CMS disks be shared either locally or across an RSCS network. It has been used to manage tool collections and conferences accessed by ...
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TOOLS, a disk and conference manager, is an experimental system that lets files on CMS disks be shared either locally or across an RSCS network. It has been used to manage tool collections and conferences accessed by tens of thousands of people, but is also suitable for disks and conferences used by just a few people. A variety of commands, such as Subscribe, Inform, Replace, and Regress are available.
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