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Lecture Notes
in Economics and
Mathematical Systems
Operations Research, Computer Science, Social Science
Edited by M. Beckmann, Providence, G. Goos, Karlsruhe, and
H. P. Kunzi, Zurich
75
GI
Gesellschaft fUr Informatik e. V.
Bericht Nr. 3
1. Fachtagung Uber
Prog ram mi ersprachen
MUnchen, 9.-11. Marz 1971
Herausgegeben 1m Auftrag
der Gesellschaft fUr Informatik
von Hans Langmaack und Manfred Paul
Spri nger-Verlag
Berlin' Heidelberg· New York 1972
Advisory Board
H. Albach· A. V. Balakrishnan' F. Ferschl . R. E. Kalman' W. Krelle . G. Seegmuller
N. Wirth
Prof. Dr. Hans Langmaack
Institut fUr Angewandte Mathematik
der Universitat des Saarlandes
Prof. Dr. Manfred Paul
Gesellschaft fur Informatik
Mathematisches Institut
der Technischen Universitat Munchen
AMS Subject Classifications (1970): 68A05, 68A30
ISBN-13:978-3-S40-060S1-2 e-ISBN-13 :978-3-642-80718-3
DOl: 10.1007/978-3-642-80718-3
This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned,
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Under § 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher,
the amount of the fee to be determined by agreement with the publisher.
© by Springer-Verlag Berlin' Heidelberg 1972. Library of Congress Catalog Card Number 72-91929.
Vorwort
Programmiersprachen gehoren seit den Anfangen der Entwicklung des
Fachgebietes Informatik zu dessen inner stem Kern. Dabei faBt der
Begriff "Programmiersprachen" eine Reihe von Gegenstanden der In
formatik zusammen, die insgesamt auf das Ziel gerichtet sind, den
Benutzern von Rechenanlagen die Programmierung wesentlich zu
erleichtern. Unter diesen Gegenstanden finden sich vor allem:
Prinzipien ftir Entwur·f und Entwicklung von
Programmiersprachen,
Definition von Programmiersprachen,
Techniken des Ubersetzerbaus ftir Programmier
sprachen.
Wurden Programmiersprachen zu Beginn der Entwicklung hauptsachlich
unter dem Gesichtspunkt des Stapelbetriebes behandelt, so erlaubt
seit einigen Jahren die Ausstattung groBer Rechenanlagen mit ent
sprechenden Betriebssystemen tiber Stapelbetrieb hinaus auch Dialog
betrieb. Diese Betriebsart hatte selbstverstandlich Rtickwirkungen
auf die Untersuchungen tiber Programmiersprachen. Beispielsweise
sind dadurch Fragen der inkrementierenden Ubersetzung wieder aktuell
geworden, die schon frtiher gelegentlich behandelt wurden. In ganz
nattirlicher Weise hat sich damit der Problemkreis auf Dialogbetrieb
ausgedehnt, so daB der GI-FachausschuB ftir Programmiersprachen auch
Dialogsprachen in die Tagungsthemen einbezogen hat.
Die Aufforderung zur Einsendung von Vortragsmanuskripten zu den
genannten Themen fand ein erfreulich starkes Echo. Dies war urn so
ermutigender, als auch die Zahl der Teilnehmer unerwartet groB war.
Die lebhaften Diskussionen zeigten ein auBerst reges Interesse an den
Vortragen und den dabei angeschnittenen Fragen.
Den Vortragenden sei deshalb an dieser Stelle sehr herzlich gedankt
ftir ihre Beitrage zur ersten Fachtagung der Gesellschaft ftir Infor
matik tiber Programmiersprachen. Sie waren es vor allem, die den
Erfolg der Tagung ermoglicht haben. Daneben gilt unser Dank allen
Teilnehmern, die durch Diskussionsbeitrage geholfen haben, die Ta
gung lebendig zu gestalten. SchlieBlich mochten wir allen Mitarbei
tern danken, die die organisatorischen Arbeiten zur Vorbereitung
und zur DurchfUhrung der Tagung so erfolgreich abgewickelt haben.
Mtinchen, den 1.2.1972 die Herausgeber
Inhaltsverzeichnis
Implementation of the Programming Language Pascal
R. SCHILD •
A Systems Programming Language
W. A. WULF . • • . . . 14
The Programming Language PS 440 as a Tool for Implementing a
Timesharing System
G• R• SAP PER • • . . . . . . . . 43
Codeerzeugung und Codeoptimierung ftir eine maschinennahe Program
miersprache
K. LAGALLY 50
Translator Functions for Compiler Description
K. ALBER 60
Design of a Versatile Precedence Parsing System
R. ZIMMER • . . . . . . . . . . . • 79
AIDA, ein Dialogsystem und seine Implementierung in ALGOL
K.-H.MOHN, M. ROSENDAHL und H.P. ZOLLER ..... 97
Partitioned Grammars and Syntax Analyzers
F. SCHWENKEL • 114
Uberblick tiber die ALGOL 68-Implementierung an der TU Mtinchen
H. SCHEIDIG und H. WOSSNER . . • . . • .....• 140
A structural Model for Dialog Languages
I. KUPKA. • • • • • 1 57
The Structure of a Flexible and Efficient Compiler for Algorithmic
Conversational Languages
H.A. SCHMID • • • • • 169
Programmierter Dialog zur Erzeugung von Lehrprogrammen
K.-D. GRAF • • • • • 185
VI
Uber den Einsatz von Makroprozessoren im Generatorteil eines
Ubersetzersystems
G. HELDMANN und H.T. KRUGER. • . . . • • . • . • • . • 199
RTS - Eine Sprache zur Beschreibung von Registernetzen
H. Hoehne • • . . . . . • 221
structural Similarity of Programs and Some Concepts of Algorithmic
Method
K. ~uLiK I ••••••••••••••••••••••••• 249
AUTORENA])~SSEN
K. ALBER, IBM Laboratories, Dept. 3247, 703 Boeblingen, Postfach 210.
KAREL CULIK, Brno - Nerudova 8, Czechoslovakia.
KLAUS-DIETER GRAF, 1 Berlin 15, UhlandstraEe 29.
G. HELDMANN, Firma Siemens Systemprogrammierung SP 3.1, 8 MUnchen 25,
BaierbrunnerstraEe 3.
HAROLD HOEHNE, Inst. f. Nachrichtenverarbeitung, T.H. Darmstadt, Prof.
Dr. Ing. R. Piloty, 61 Darmstadt, ArheilgerstraEe 1.
H.-T. KRUGER, Firma Siemens Systemprogrammierung SP 3.1, 8 MUnchen 25,
BaierbrunnerstraEe 3.
INGBERT KUPKA, Institut fUr·lnformatik der Universitat, 2 Hamburg 13,
SedanstraEe 19.
K. LAGALLY, Rechenzentrum der Technischen Universitat, Arbeitsgruppe
fUr Betriebssysteme, 8 MUnchen 2, ArcisstraEe 21.
KARL-HEINZ MOEN, Rechenzentrum der Ruhr-Universitat, 463 Bochum,
BuscheystraEe, Geb. NA.
ROSENDAHL, Rechenzentrum der Ruhr-Universitat, 463 Bochum,
~~NFRED
BuscheystraEe, Geb. NA.
GERD SAPPER, Rechenzentrum der Technischen Universitat MUnchen,
A!'beitsgruppe fUr Betriebssysteme, 8 Mti.nchen 2, ArcisstraEe 21.
R. SCHILD, Fachgruppe Computer-Wissenschaften, Eidgen. Technische
Hochschule, CH-8006 ZUrich, ClausiusstraEe 55.
HANS ALBRECHT SCHMID, Institut fUr Informatik, Universitat Karlsruhe,
75 Karlsruhe, EnglerstraEe 2.
F. SCHWENKEL, University of Notre Dame, Computer Science Department.
H. WOSSNER, Mathematisches Institut der Technischen Universitat
MUnchen, 8 MUnchen 2, ArcisstraEe 21.
WILLIAM A. WULF, Carnegie-Mellon University, Pittsburgh, PA/USA.
REINER Siemens AG, Dv T Systemprogramme, 8 MUnchen 25,
ZI~mER,
HofmannstraEe 51.
HANSPETER ZOLLER, Rechenzentrum der Ruhr-Universitat, 463 Bochum.
BuscheystraEe, Geb. NA.
IMPLEMENTATION OF THE PROGRAMMING LANGUAGE PASCAL
by R. Schild
The programming language Pascal was developed at the
Federal Institute of Technology ( ETH ) in ZUrich by Prof.
N. Wirth and implemented by his assistants U. Ammann, E.
Marmier and myself. The language evolved in the course of
a project for extending and generalizing Algol 60 , a pro
ject which also produced the language Algol W •
Immediately the question will be asked: Why another pro
gramming language? Isn't the confusion already large enough?
Our answer is best given by stating the goals we had set
ourselves:
On the one hand we wanted to create a tool which allows
the programmer to write his programs in a natural, clear,
and concise way. This requirement would also make the langu
age well suited for teaching -- not for teaching the language
itself (although that is of course desirable, and unfortuna
tely not true of many existing programming languages), but
for teaching the art of programming, a quality which most
languages unfortunately are lacking.
On the other hand our aim was to develop an implementation
which is both reliable and efficient, efficient in the sense
that the compiler should produce fast-running code, and should
do so in little time.
As mentioned before, Algol 60 was used as a basis for
Pascal, since it meets the demands in respect to teaching
better than any other standard language. However, Algol
includes certain construction principles which we did not
want to incorporate in Pascal, mostly because they would
have downgraded its efficiency. On the other hand, Pascal
contains extensions of Algol, primarily in the domain of data
structures.
2
The language (syntax and semantics) and its compiler were
developed simultaneously. This provided us with the possibi
lity to modify or entirely exclude constructions which could
not be implemented efficiently.
Implementation
The Pascal System as it is implemented at the ETH consists
of two parts: the monitor and the compiler.
The monitor (written in assembly language) is loaded into
memory by the operating system. It contains routines to
load the compiler, to load the compiled program, to transfer
control to a loaded program, and the file handling routines.
The monitor remains in core during compilation and during
execution of a program.
The compiler (written in Pascal) is loaded by the monitor
and receives control from it. It then processes the user
program, producing absolute (executable) code which permits
faster loading. Since the compiler itself is also a Pascal
program and is kept in absolute code, it, too, can be loaded
very quickly.
After having returned control to the monitor, the compiler
is overwritten by the user program which then receives control
from the monitor.
Let us now take a closer look at the language, the compiler,
and the code which it produces.
To attain high efficiency, we constructed the compiler
as a ~ne-pass-system, thereby avoiding the need for repeated
input/output of scratch files. To make the syntax analysis
as simple as possible we used a top-down method, representing
the syntax as a set of pseudo-finite automata, and using a
one-symbol-lookahead scheme. The compiler closely resembles
the syntax: each automaton corresponds to a procedure.
The compiler can be divided into three distinct parts:
