摘要:

AbstractThe paper addresses the problem of automating microprogram generation, starting from a high‐level language (namely from a subset of PL/1). The microprogram synthesis process is structured in four steps in a highly hierarchical way; each step may be viewed as an independent process which uses formal representations for both data (i.e. the input program) and machine specifications. The translation system is based on a microcode model built on a formal definition of microoperations, microinstruction semantics, and relationships among microinstruction

ISSN:0038-0644    

DOI:10.1002/spe.4380121102

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractTwo styles of operating system implementation based on the use of monitors and processes, respectively, are identified, and arguments for a basic equivalence of these systems despite large stylistic differences are presented. The ‘Lauer‐Needham Duality Hypothesis’ states that the two styles are equivalent, both in terms of ease of programming and in efficiency of the resulting systems. A domain for which the first part of this claim holds is outlined, and data affirming the essential equivalence of performance within that domain are presented. An operating system based on the Cambridge CAP system, called SIMOS, was simulated for a wide range of hardware configurations and job loads. SIMOS is written using a module concept that allows an individual module to be interpreted as a monitor in one run and as a process in another. Runs using a monitor to control access to some data can be compared with runs using a process to control access to the same data. The throughput and response time for the two styles of system were found to be identical in most cases. However, a degradation in response time occurred in a process‐based system when the job load and the low level scheduling policy were poorly

ISSN:0038-0644    

DOI:10.1002/spe.4380121103

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractA practical approach to the development of a high‐quality, re‐usable code generator is described in this paper. This code generator produces code for the Prime 64V mode architecture, but the methodology used is generally applicable to the construction of compilers for most architectures. The code generator accepts a tree‐structured intermediate form, linearized and represented as a file of integers. This intermediate form uses high‐level operators, minimizing work by compiler front‐ends that use it and providing a number of advantages in the code generation process. The output of the code generator is assembly language. This tool was found to considerably extend the capabilities of students in a graduate compiler class and has been used in the construction of Pascal and C

ISSN:0038-0644    

DOI:10.1002/spe.4380121104

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractIn this paper a cost model for software conversion projects is developed. The model is based upon three variable parameters:L(thousands of lines of source code),N(the total number of programs being converted) and E (the conversion software inefficiency). All other parameters included in the model are constant coefficients which can vary from one type of conversion to another.An analysis of the resulting model yields four major conclusions: (1) There is an optimum investment that should be made in conversion software for each conversion project. (2) As the total number of lines to be converted increases, it is cost‐effective to increase the investment in conversion software. (3) If conversion software is reused for a second project, it is worthwhile to invest additional effort (and/or funds) in upgrading the software. (4) As the size of the conversion increases the cost per line decreases to a lower limi

ISSN:0038-0644    

DOI:10.1002/spe.4380121105

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper describes a file server which was specifically designed to be the file store for a number of personal microcomputers attached to a local area network. In particular these personal machines (clients) have a very limited amount of memory with which to interface to the file server. The filing system supports an hierarchical directory structure with a simple capability‐like protection mechanism. Both the operations and communication protocol supported by the file server are chosen to make a client computer's interface code simple. Special attention is given to speeding up certain frequently used processor‐bound operations. Various aspects of the implementation are discussed, together with some suggested improveme

ISSN:0038-0644    

DOI:10.1002/spe.4380121106

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractFfgis a simple database system that consists of a set of many independent programs, called primitives, each of which performs a single operation. The user composes primitives by connecting the output of one to the input of the next to achieve a computation. Because they are independent, primitives are easily modified or replaced, and one can add programs to the set of primitives. Unlike the strongly typed interconnections provided by many languages, interconnections offfgprimitives are not type‐checked. The implementationffgis also novel becauseffgprimitives are constructed out of lower level primitives instead of conventional programs. The selection of primitives, the type checking mechanism and the implementation are discusse

ISSN:0038-0644    

DOI:10.1002/spe.4380121107

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractLisp is restricted in application because of d the unpredictable delays introduced by garbage collection. Incremental garbage collectors eliminate the delays, but are less efficient overall. We present a semi‐incremental algorithm that reduces the delays and is, moreover more efficient than the mark‐scan algorithm from which it is derived. The mark‐scan algorithm is explained it consists of a mark phase followed by a sweep phase. The sweep phase can be performed incrementally, but the mark phase cannot. If this modification is made, our semi‐incremental algorithm is derived. Using the new algorithm the delay on garbage collection is proportional to the amount of heap actually in use, not the size of the heap. Allocating a cell takes a variable amount of time, depending on the proportion of the heap in use. Comparing the number of operations in the old and new algorithms, we see that the new algorithm is more efficient. The new algorithm was used as part of a Lisp implementation on an LSI‐11/03 and found to be

ISSN:0038-0644    

DOI:10.1002/spe.4380121108

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractWe show that informing a lazy evaluator that the APPEND operator is associative reduces the overall worst case performance from O(n2) to O(n).

ISSN:0038-0644    

DOI:10.1002/spe.4380121109

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0038-0644    

DOI:10.1002/spe.4380121101

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY