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Implementing a PASCAL compiler on an 8085A system
engine, a port congestion problem was encountered. In order to interface a variety of peripherals simultaneously to the Microengine, an expression based on the 6502 microprocessor has been developed. The paper describes this and the factors that influenced its design - both hardware and software designs are included.
Software Daniels, M C and Pemberton, S '1 mplementing a PASCAL compiler on an 8085A system' Microcomputer Applications Vol 4 No 3 pp 144-150 This paper describes a practical implementation of the PASCAL P-compiler on a commercial system based around the 8085 with multiple-drive floppy discs. The project objective was to be able to compile and run PASCAL programs on the target machine. The compiler generates P-code and so the major part of the work involved resdesigning the P-code assembler and generating a runtime environment (a number of alternatives are discussed) for the resultant assembler output. Since the target machine has a limited (12k) RAM available, a paging system was developed (and is described here) to enable large programs to be executed.
Davis, H A 'Reducing roundoff errors in microprocessor based calculations' Computer Design Vol 20 No 2 (February 1981) pp 113-117 Errors are inevitable when dealing with a finite representation of a real number, such as the binary code used in computers. These errors can never be eliminated, but they can be controlled and their effects esti mated. This paper identifies the sequence of operations that produces the least error when using floating-point arithmetic during expression evaluation, reducing the need for extended precision arithmetic. Multiple-precision computations reduce arithmetic error but incur a large penalty in terms of program size, data storage requirements and execution time.
vol 5 no 5june 1981
Grossman, S and Jones, F 'Memory-error program evaluates reliability tradeoffs' EDN Vol 26 No 2 (21 January 1981) pp 131-137 RAM-error-correction procedures provide benefits, and entail problems, that depend on memory organization, failure rate and maintenance. Systems with short mean time to error (MTTE) can profit significantly when errorcorrection combines with periodic hard- and soft-error maintenance. The Microsoft BASIC program shown here implements a probabilistic memory reliability model - it calculates the probability of and mean time to double-bit hard and soft errors in any word of a xl-bit array. This is a two part series; part two is described below. 'Analyze size, maintenance factors to ensure memory reliability' EDN Vol 26 No 3 (4 February 1981) pp 155-158 The second part of this series examines graphical presentations of memorysystem reliability and the effects of various schedules developed by the program. Though the system-reliability model described does not establish a minimum acceptable reliability level, it can help to determine the tradeoffs involved in designing for the chosen level Observations made from the graphical comparisons are that larger systems lead to lower reliability; fewer errors come from denser devices; high soft-error rates affect system reliability; reliability decreases as devices loss goes up; and the effects of hard-error maintenance on doublebit-hit probability and of short maintenance intervals on large systems.
Press, L 'An overview of the CP/M software market' Mini-Micro Systems Vol 14 No 22 (February 1981 ) pp 167-170 The availability of CP/M on many different manufacturers' systems has formed the backbone of the personalcomputing software industry - more than 120 companies now offer CP/M systems and applications software. This overview looks at the minimum hardware configuration, the systems software and high level languages available under.CP/M. Figures are also given for accounting packages, wordprocessing and utility programs and
specialized commercial software for CP/M systems. A brief background and history of CP/M is also included. Watkins, J 'The conversion of PASCAL into microprocessor code' Microcomputer Applications Vol 4 No 3 pp 151-165 Using a sample PASCAL program, its equivalent P-code form can be generated using a PASCAL P-compiler (from ETH Laboratories, Zurich, Switzerland). The nature of P-code is explained together with the operation of the virtual stack machine invoked by use of the ETH interpreter. By modifying the interpreter and developing a set of Stage 2 macros for its individual case options, the P-code listing can be translated into a microprocessor language.
Whinston, A B and Holsapple, C W 'DBMS for micros' Datamation Vol 27 No 4 (April 1981) pp 1 6 5 167 A genuine database management system (DBMS) should improve the productivity of custom program ming operations compared to ordinary filehandling methods. The old system comprising files, pointers, updates and file structures - is replaced by simple graphic representation of the data network and its logical relationship (the schema). The authors list the ways in which a schema, transferred to a computer by a data definition language, can increase software productivity. An example, using a model of an aircraft base, is also given.
Applications Collie, A A ' Microprocessor-based controls for white goods' Electronics & Power Vol 27 No 3 (March 1981) pp 2 3 6 239 Market forces are compelling domestic-appliance manufacturers to design microprocessor-based control into their products. The movement from space conscious design to microprocessor control has been rapid, and not just in 'up-market' ranges.
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Software Daniels, M C and Pemberton, S '1 mplementing a PASCAL compiler on an 8085A system' Microcomputer Applications Vol 4 No 3 pp 144-150 This paper describes a practical implementation of the PASCAL P-compiler on a commercial system based around the 8085 with multiple-drive floppy discs. The project objective was to be able to compile and run PASCAL programs on the target machine. The compiler generates P-code and so the major part of the work involved resdesigning the P-code assembler and generating a runtime environment (a number of alternatives are discussed) for the resultant assembler output. Since the target machine has a limited (12k) RAM available, a paging system was developed (and is described here) to enable large programs to be executed.
Davis, H A 'Reducing roundoff errors in microprocessor based calculations' Computer Design Vol 20 No 2 (February 1981) pp 113-117 Errors are inevitable when dealing with a finite representation of a real number, such as the binary code used in computers. These errors can never be eliminated, but they can be controlled and their effects esti mated. This paper identifies the sequence of operations that produces the least error when using floating-point arithmetic during expression evaluation, reducing the need for extended precision arithmetic. Multiple-precision computations reduce arithmetic error but incur a large penalty in terms of program size, data storage requirements and execution time.
vol 5 no 5june 1981
Grossman, S and Jones, F 'Memory-error program evaluates reliability tradeoffs' EDN Vol 26 No 2 (21 January 1981) pp 131-137 RAM-error-correction procedures provide benefits, and entail problems, that depend on memory organization, failure rate and maintenance. Systems with short mean time to error (MTTE) can profit significantly when errorcorrection combines with periodic hard- and soft-error maintenance. The Microsoft BASIC program shown here implements a probabilistic memory reliability model - it calculates the probability of and mean time to double-bit hard and soft errors in any word of a xl-bit array. This is a two part series; part two is described below. 'Analyze size, maintenance factors to ensure memory reliability' EDN Vol 26 No 3 (4 February 1981) pp 155-158 The second part of this series examines graphical presentations of memorysystem reliability and the effects of various schedules developed by the program. Though the system-reliability model described does not establish a minimum acceptable reliability level, it can help to determine the tradeoffs involved in designing for the chosen level Observations made from the graphical comparisons are that larger systems lead to lower reliability; fewer errors come from denser devices; high soft-error rates affect system reliability; reliability decreases as devices loss goes up; and the effects of hard-error maintenance on doublebit-hit probability and of short maintenance intervals on large systems.
Press, L 'An overview of the CP/M software market' Mini-Micro Systems Vol 14 No 22 (February 1981 ) pp 167-170 The availability of CP/M on many different manufacturers' systems has formed the backbone of the personalcomputing software industry - more than 120 companies now offer CP/M systems and applications software. This overview looks at the minimum hardware configuration, the systems software and high level languages available under.CP/M. Figures are also given for accounting packages, wordprocessing and utility programs and
specialized commercial software for CP/M systems. A brief background and history of CP/M is also included. Watkins, J 'The conversion of PASCAL into microprocessor code' Microcomputer Applications Vol 4 No 3 pp 151-165 Using a sample PASCAL program, its equivalent P-code form can be generated using a PASCAL P-compiler (from ETH Laboratories, Zurich, Switzerland). The nature of P-code is explained together with the operation of the virtual stack machine invoked by use of the ETH interpreter. By modifying the interpreter and developing a set of Stage 2 macros for its individual case options, the P-code listing can be translated into a microprocessor language.
Whinston, A B and Holsapple, C W 'DBMS for micros' Datamation Vol 27 No 4 (April 1981) pp 1 6 5 167 A genuine database management system (DBMS) should improve the productivity of custom program ming operations compared to ordinary filehandling methods. The old system comprising files, pointers, updates and file structures - is replaced by simple graphic representation of the data network and its logical relationship (the schema). The authors list the ways in which a schema, transferred to a computer by a data definition language, can increase software productivity. An example, using a model of an aircraft base, is also given.
Applications Collie, A A ' Microprocessor-based controls for white goods' Electronics & Power Vol 27 No 3 (March 1981) pp 2 3 6 239 Market forces are compelling domestic-appliance manufacturers to design microprocessor-based control into their products. The movement from space conscious design to microprocessor control has been rapid, and not just in 'up-market' ranges.
209