A tutorial-like overview on formal methods for the specification of reactive systems is given. State transition systems such as ATNs, statecharts, and SDL are discussed. Petri nets and logic-based languages are introd...
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A tutorial-like overview on formal methods for the specification of reactive systems is given. State transition systems such as ATNs, statecharts, and SDL are discussed. Petri nets and logic-based languages are introduced as alternatives;examples show their respective applicability. programming-oriented approaches such as ESTEREL, CSP, or CCS are depicted. Finally, the different principles are compared.
The problem of automatic loop parallelization has received a lot of attention in the area of parallelizing compilers. Automatic loop parallelization can be achieved by several algorithms. In this paper, we address the...
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The problem of automatic loop parallelization has received a lot of attention in the area of parallelizing compilers. Automatic loop parallelization can be achieved by several algorithms. In this paper, we address the problem of time optimal parallelization of loops with conditional jumps. We prove that even for machines with unlimited resources there are simple loops for which no semantically and algorithmically equivalent time optimal program exists.
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.
The use of a programming language for describing hardware is proposed in this paper. The presented approach, based on minor extensions of C++, gives an attractive way to program computers with reconfigurable hardware ...
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The use of a programming language for describing hardware is proposed in this paper. The presented approach, based on minor extensions of C++, gives an attractive way to program computers with reconfigurable hardware elements (i.e. FPGAs). It can also be used as a common implementation-level language for hardware-software codesign frameworks. The proposed approach differs from other codesign methodologies due to the use of a single, object oriented, notation for all design levels;from the most abstract OMT notations, where the system's functionality and requirements are first captured, to the detailed implementation-level C++ code.
In this paper a version of unstable merging of two neighbouring segments in an one-dimensional array is presented. The algorithm runs in O(1) space and in linear time. It is based on stable merging,1but its working ar...
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In this paper a version of unstable merging of two neighbouring segments in an one-dimensional array is presented. The algorithm runs in O(1) space and in linear time. It is based on stable merging,1but its working area is not chosen outside merged segments; instead it occupies the end of one of them. Despite the fact that there are no restrictions on segment sizes, the algorithm is the fastest in its class of those published so far.
Functional acceptance trials had to be carried out on 250,000 lines of code in just two weeks on the LACES system at London Airport. Complicated user interactions precluded parallel running and absolute confidence in ...
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Functional acceptance trials had to be carried out on 250,000 lines of code in just two weeks on the LACES system at London Airport. Complicated user interactions precluded parallel running and absolute confidence in these trials was therefore essential. This paper describes the general principles behind the approach which was successfully developed for the purpose, based partly on emulating the Post Office technique for testing Automatic Telephone Exchanges.
With its fundamentally dynamic nature, software requires constant modifications to meet new specifications, improve performance, or correct program errors. Documentation keeps track of those changes and records the up...
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With its fundamentally dynamic nature, software requires constant modifications to meet new specifications, improve performance, or correct program errors. Documentation keeps track of those changes and records the updated program configuration, internal links, and operation process. Unfortunately, like most clerically oriented task, manual documentation is tedious and often error-prone. Software that automatically documents changes is the obvious solution. Author reports on a set of high-level documentation packages, which are part of an integrated software package called Softools, developed for a large number of mainframes and minicomputers. The software operates with virtually any computer language, and built-in guide posts lead the user through the operation of each tool.
The problems of consistency between a computer program and its specification are discussed. The presence of axiomatic definitions of abstract types provides a mechanism for proving this consistency. Two approaches for...
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The problems of consistency between a computer program and its specification are discussed. The presence of axiomatic definitions of abstract types provides a mechanism for proving this consistency. Two approaches for the definition of the abstract types are considered - within the programming language Euclid and algebraic technique.
The general language and opensource Python, coupled with its scientific libraries, offers an interesting alternative to Matlab, Java, and C++ for the development of scientific applications. In this context, authors pr...
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In this paper, we examine the availability and utility of idle memory in workstation clusters. We attempt to answer the following questions. First, how much of the total memory in a workstation cluster can be expected...
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In this paper, we examine the availability and utility of idle memory in workstation clusters. We attempt to answer the following questions. First, how much of the total memory in a workstation cluster can be expected to be idle? This provides an estimate of the opportunity for hosting guest data. Second, how much memory can be expected to be idle on individual workstations? This helps determine the recruitment policy - how much memory should be recruited on individual hosts? Third, what is the distribution of memory idle-times? This indicates how long guest data can be expected to survive; applications that access their data-sets frequently within the expected life-time of guest data are more likely to benefit from exploiting idle memory. Fourth, how much performance improvement can be achieved for off-the-shelf clusters without customizing the operating system and/or the processor firmware? Finally, how long and how frequently might a user have to wait to reclaim her machine if she volunteers to host guest pages on her machine? This helps answer the question of social acceptability. To answer the questions relating to the availability of idle memory, we have analyzed two-week long traces from two workstation pools with different sizes, locations, and patterns of use. To evaluate the expected benefits and costs, we have simulated five data-intensive applications (0.5 GB-5 GB) on these workstation pools.
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