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Writing a compiler for a small machine with minimal software support can be quite difficult because the program is long and debugging aids are usually inadequate. In addition, the usual techniques for compiler writing tend to produce programs which are quite large when compared to, for example, a BASIC interpreter. This frustrates efforts for producing compilers on small machines. We describe a method which can be used to reduce the size of a compiler and simultaneously provide good debugging tools. The resulting compiler sacrifices little in terms of execution speed (in part because compilers on minicomputers are often I/O bound). We have used this method to write an MPL [1] compiler for a Microdata 32/S minicomputer. The compiler requires approximately 12K bytes of memory as opposed to 32K bytes required by the compiler produced by the manufacturer, and compiles at essentially the same speed. Appendix II outlines the syntax of the MPL language and is included to illustrate the size of the language being compiled. MPL is based on PL/I and is quite similar to the PL/M* [2] language developed by the INTEL Corporation. The method described here uses an interpretive language for writing the compiler. Thus the interpreter is the only machine language program written. We coded the interpreter in MPL and used a cross compiler to compile it, however, the interpreter could have been easily coded in assembly language. Figure 1 illustrates the savings of the interpretive language over machine code. The procedure IF_STAT is typical of a routine which might appear in a recursive descent compiler for MPL. The gain in space occurs because machine language instructions carry too much information content when applied to a special purpose (such as compiling). Note for example that a subroutine call for the Microdata requires 6 bytes, but all that is really needed is an opcode to indicate a call and a byte to indicate which of a few subroutines is to be called.

In earlier work on anticipation and prompting systems for programming languages it was recognized that a more formal approach to development of such interactions with programmers at display terminals was needed. It was observed that the bulk of the data involved in these interactions was in the displays themselves and that certain display drivers operated on action strings similar to those in production language systems. The development of special Floyd-Evans production languages oriented toward a visual interactive environment was therefore undertaken. Based on two experimental interpreters which have been implemented, the language itself has now been substantially refined and compilers for a common language have been designed with one being implemented. In the first implementation which was accomplished on a Datapoint 2200, a substantial portion of the effort was devoted to a pedagogic display of the parsing process. In the second implementation on an Interdata 85, all of the programming was made reentrant so that multiple users can be served using the same or different target languages. Furthermore, some of the basic functions were reduced to microcode, although it was not possible to carry this as far as had been hoped. It was also learned during development of the second system that left-part matching and right-part replacement could be treated as generalized actions—thus simplifying the internal structure of the interpreter. Development of these systems is part of ongoing research with programming languages and automated programmer assistance.

Minicomputers are the newest tool adopted by businesses to improve their efficiency and profitability. The typical small business which seeks such a system, however, lacks the technical skills which have characterized computer installations in the past. They also lack the financial resources to establish such a function. As a result, these businesses have turned to systems houses, consultants and the hardware vendors for a “turnkey” approach. “I just want to plug it in and run it” is the typical businessman's comment. Unfortunately, that approach is frought with problems. The turnkey vendor does not have the same understanding of the small business as its management has. The vendor may have a “package” which he wants to fit his customer into, rather than fitting the programs to the business. There may be contract problems - and most lawyers for small businesses do not understand the special status of a computer turnkey system. There may be problems in training operators or converting data. And on and on. These problems can be avoided. Proper planning and knowing when to get help and from where will go a long way. The purpose of this presentation will be to discuss these problems and solutions in the context of the small business.

Attached Processing, a new concept in business data processing, specifies a new system architecture constituting an on-line computer system of arbitrary size, made up of an arbitrary number of functionally dispersed processors which nevertheless maintain common data bases. Information stored in such a system is immediately accessible, under user-configured security controls, by any processor attached to it. Such a system can expand by simple accretion, without economic penalty. To obtain more processing throughput, one attaches more processors. To obtain more data storage, one attaches additional disk drives as needed. In its practical realization, Attached Processing assumes the form of an Attached Resource Computer. The Attached Resource Computer does not employ a central, controlling host computer. System control is decentralized. Failure of any individual processor in the system cannot bring all processing to a halt. Functional reconfigurations are easy since no processor is hard-wired to a specific task or tasks.

A computer system used to support the technical research department of Conti Commodity is described. The system is installed on a Data General Eclipse S/200 computer and has been in operation since June, 1976. It is centered around a 12MB database of commodity prices and includes plotter and communication software.

A survey of minicomputer data base management systems was conducted to determine the current state of the industry. The results of the survey are highlighted in this paper to provide a broad view of the features of commercially available mini-data base systems. Among the topics presented are hardware requirements, software implementation, data independence, binding, integrity, privacy controls, installation base, availability, and user considerations. In addition, the relationship between the growth of the minicomputer market and mini-DBMS market in the second half of the 70's is emphasized.

A 12-man-year process control software project has been successfully completed in 12 months without interruption of the production process of CERN PS accelerators. After 6 months of careful preparation by a small team, 9 man-years of software, i.e. around 100 control programs amounting to more than 40'000 instructions, have been produced in 6 months by 6 experienced full-time software engineers and 24 part-time engineers and technicians, part of whom had never programmed before. The delivered product met the users specifications, was completed within schedule, conformed to the standards and was fully documented.

This paper reports on the implementation of a powerful data manipulation language (DML) of a data base system for minicomputers. The technique of language preprocessing is employed: The preprocessor translates each DML-statement into an internal form; however, in addition to a mere translation of statements the preprocessor has the function of executing so called 'compile-time tasks', i.e. those subtasks of the evaluation of a DML-statement, which can be done at compile-time already. This processing takes place in the course of program compilation and thus the size of the run-time module as well as execution-times can be reduced. The data base system FADABS is used to illustrate this approach.

Basic is a general purpose programming language commonly used in business applications. There are many versions of Basic with varying capabilities, ranging from simple games to large multi-terminal business applications. However, Basic is seldom used to implement a large realtime control system. The purpose of this paper is to describe a realtime control system and discuss the advantages and the disadvantages of implementing the system using Basic.