Table of Contents

American National Standard for Information Systems

Programming Languages

Forth

Secretariat
Computer and Business Equipment Manufacturers Association
Approved: March 24, 1994
American National Standards Institute, Inc.

This is a working document of Technical Committee X3J14 which represents the last draft of ANS Forth submitted to ANSI for publication. Permission is hereby granted to copy this document provided that it is copied in its entirety without alteration or as altered by (1) adding text that is clearly marked as an insertion; (2) shading or highlighting existing text; and/or (3) deleting examples.

Specifically, permission is granted to use this working document as the foundation for textbooks, system manuals, and online documentation so long as the requirements in the preceding paragraph are met and the resulting product addresses a technical need that is not practically met by the official ANS.

NOTE: This file is provided as a working document of the TC for public review and comment as well as documentation uses described above. It is not intended as a substitute for the official ANS Forth document published by ANSI. In the event of conflict, only the printed document X3.215-1994 represents the official ANS Forth.

To obtain the official standard, please contact the American National Standards Institute Sales Department, at (212) 642-4900 or FAX (212) 302-1286, or Global Engineering Documents, at (800) 854-7179 or FAX (303) 843-9880, and request Document X3.215-1994. Thank you very much for your interest.

Foreword

(This foreword is not a part of American National Standard X3.215-1994)

Forth is a language for direct communication between human beings and machines. Using natural-language diction and machine-oriented syntax, Forth provides an economical, productive environment for interactive compilation and execution of programs. Forth also provides low-level access to computer-controlled hardware, and the ability to extend the language itself. This extensibility allows the language to be quickly expanded and adapted to special needs and different hardware systems.

Forth was invented by Mr. Charles Moore to increase programmer productivity without sacrificing machine efficiency. Forth is a layered environment containing the elements of a computer language as well as those of an operating system and a machine monitor. This extensible, layered environment provides for highly interactive program development and testing.

In the interests of transportability of application software written in Forth, standardization efforts began in the mid-1970s by an international group of users and implementors who adopted the name Forth Standards Team. This effort resulted in the Forth-77 Standard. As the language continued to evolve, an interim Forth-78 Standard was published by the Forth Standards Team. Following Forth Standards Team meetings in 1979, the Forth-79 Standard was published in 1980. Major changes were made by the Forth Standards Team in the Forth-83 Standard, which was published in 1983.

The first meeting of the Technical Committee on Forth Programming Systems was convened by the Organizing Committee of the X3J14 Forth Technical Committee on August 3, 1987, and has met subsequently on November 11-12, 1987, February 10-12, 1988, May 25-28, 1988, August 10-13, 1988, October 26-29, 1988, January 25-28, 1989, May 3-6, 1989, July 26-29, 1989, October 25-28, 1989, January 24-27, 1990, May 22-26, 1990, August 21-25, 1990, November 6-10,1990, January 29-February 2, 1991, May 3-4, 1991, June 16-19, 1991, July 30-August 3, 1991, March 17-21, 1992, October 13-17, 1992, January 26-30, 1993, June 28-30, 1993, and June 21, 1994.

Requests for interpretation, suggestions for improvement or addenda, or defect reports are welcome. They should be sent to the X3 Secretariat, Computer and Business Equipment Manufacturers Association, 1250 Eye Street, NW, Suite 200, Washington, DC 20005.

X3 Membership

This standard was processed and approved for submittal to ANSI by the Accredited Standards Committee on Information Processing Systems, X3. Committee approval of this standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, the X3 Committee had the following members:

James D. Converse, Chair Donald C. Loughry, Vice-Chair Joanne Flanagan, Secretary

Producer Group                          Name of Representative
--------------                          ----------------------
AMP Incorporated                        Edward Kelly
                                        Charles Brill (Alt.)

AT&T/NCR Corporation                    Thomas W. Kern
                                        Thomas F. Frost (Alt.)

Apple Computer, Inc.                    Karen Higginbottom

Compaq Computers                        James Barnes

Digital Equipment Corporation           Delbert Shoemaker
                                        Kevin Lewis

Hitachi America Ltd.                    John Neumann
                                        Kei Yamashita (Alt.)

Hewlett Packard                         Donald C. Loughry

Bull HN Information Systems Inc.        William George

IBM Corporation                         Joel Urman
                                        Mary Anne Lawler (Alt.)

Unisys Corporation                      John Hill
                                        Stephen P. Oksala (Alt.)

Sony Corporation of America             Michael Deese

Storage Technology Corporation          Joseph S. Zajaczkowski
                                        Samuel D. Cheatham (Alt.)

Sun Microsystems, Inc.                  Scott Jameson
                                        Gary S. Robinson (Alt.)

* Xerox Corporation                     Dwight McBain
                                        Roy Pierce (Alt.)

3M Company                              Edie T. Morioka
                                        Paul D. Jahnke (Alt.

Consumers Group
---------------

Boeing Company                          Catherine Howells
                                        Andrea Vanosdoll (Alt.)

Eastman Kodak Company                   James Converse
                                        Michael Nier (Alt.)

General Services Administration         Douglas Arai
                                        Larry L. Jackson (Alt.)

Guide International Inc.                Frank Kirshenbaum
                                        Harold Kuneke (Alt.)

** Hughes Aircraft Company              Harold Zebrack

National Communications Systems         Dennis Bodson

Northern Telecom Inc.                   Mel Woinsky
                                        Subhash Patel (Alt.)

** Recognition Tech Users Association   Herbert P. Schantz
                                        Edwin Hale (Alt.)

Share Inc.                              Gary AinsworthDavid Thewis (Alt.)

U. S. Department of Defense             William Rinehuls
                                        J. Pasquariello (Alt.)

U. S. Department of Energy              Alton Cox
                                        Lawrence A. Wasson (Alt.)

Wintergreen Information Services        John Wheeler

General Interest Group
----------------------

American Nuclear Society                Geraldine C. Main
                                        Sally Hartzell (Alt.)

Assn. of the Institute for Certification of Computer Professionals
                                        Kenneth Zemrowski

Nat'l Institute of Standards and Technology     
                                        Robert E. Rountree
                                        Micharl Hogan (Alt.)

Neville & Associates                    Carlton Neville
________________________

* Abstain      ** Non-Response

X3J14 Membership

At the time it approved this draft of the proposed American National Standard, the Technical Committee X3J14 on the Forth Programming Language had the following members:

Elizabeth Rather, Chair
Mitch Bradley, acting Vice-Chair
Don Colburn, Secretary
John Rible, Technical Editor
Len Zettel, Vocabulary Representative
Greg Bailey, Technical Subcommittee Chair

Organization Represented                Name of Representative
------------------------                ----------------------
ATHENA Programming, Inc.                Greg Bailey
                                        Howe Fong (Alt.)

Bradley Forthware                       Mitch Bradley

Creative Solutions, Inc.                Don Colburn

Ford Motor Company                      Leonard F. Zettel, Jr.

FORTH, Inc.                             Elizabeth Rather
                                        Dennis Ruffer (Alt.)

Institute for Applied Forth Research    Lawrence Forsley
                                        Horace Simmons (Alt.)

Johns Hopkins University, Applied Physics Lab.  
                                        John Hayes

Mephistopheles Systems                  Dave Harralson

NASA/Goddard Space Flight Center        James Rash

Nomadic Software                        John K. Stevenson

Unisyn, Inc.                            Gary Betts
                                        Stephen Egbert (Alt.)

Up and Running                          Martin Tracy

Vesta Technology                        Jack Woehr

Individual Members                      Loring Craymer
                                        John Rible
                                        E. (Jet) Thomas

X3 Liasons                              Clyde R. Camp
                                        Kathleen McMillan

The following organizations and individuals have also participated in this project as Technical Committee members, alternates, or observers. The Technical Committee recognizes and respects their contributions:

Organizations
-------------

British Columbia Inst. of Tech.  MCI Telecommunications Corp.
Computer Cowboys                 Micromotion
Computer Sciences Corp.          MicroProcessor Engineering Ltd.
Computer Strategies, Inc.        National Institute of Standards & Technology
Digalog Corp.                    NCR Medical Systems Group
Embedded Sys. Programming Mag.   Performance Packages, Inc.
Forth Interest Group (FIG)       Purdue University
H.B. Pascal & Co., Inc.          Robert Berkey Services
Harris Semiconductor             Shaw Laboratories
IBM Corporation                  Social Security Administration
IEEE                             Software Engineering
Kelly Enterprises                Texas Instruments
Laboratory Microsystems, Inc.    The Dickens Company
Maxtor Corp.

Individuals
-----------

David J. Angel  Ray Duncan      Charles Moore   Dean Sanderson
Wil Baden       Douglas Fishman Mike Nemeth     George Shaw
Robert Berkey   Tom Hand        Harry Pascal    Gerald Shifrin
Ron Braithwaite Gregory Ilg     Stephen Pelc    Robert Smith
Jack Brown      Charles Keane   Dean Perrine    Tyler Sperry
Chris Colburn   Guy M. Kelly    David C. Petty  Tom Zimmer
Ted Dickens     Andrew Kobziar  Bill Ragsdale   James Ryland
John Dorband    Martin Lascelles

AMERICAN NATIONAL STANDARD ANSI X3.215-1994 American National Standard for Information Systems

Programming Language

Forth

1. Introduction

1.1 Purpose

The purpose of this Standard is to promote the portability of Forth programs for use on a wide variety of computing systems, to facilitate the communication of programs, programming techniques, and ideas among Forth programmers, and to serve as a basis for the future evolution of the Forth language.

1.2 Scope

This Standard specifies an interface between a Forth System and a Forth Program by defining the words provided by a Standard System.

See: A.1.2 Scope

1.2.1 Inclusions

This Standard specifies:

the forms that a program written in the Forth language may take;
the rules for interpreting the meaning of a program and its data.

1.2.2 Exclusions

This Standard does not specify:

the mechanism by which programs are transformed for use on computing systems;
the operations required for setup and control of the use of programs on computing systems;
the method of transcription of programs or their input or output data to or from a storage medium;
the program and Forth system behavior when the rules of this Standard fail to establish an interpretation;
the size or complexity of a program and its data that will exceed the capacity of any specific computing system or the capability of a particular Forth system;
the physical properties of input/output records, files, and units;
the physical properties and implementation of storage.

1.3 Document organization

1.3.1 Word sets

This Standard groups Forth words and capabilities into word sets under a name indicating some shared aspect, typically their common functional area. Each word set may have an extension, containing words that offer additional functionality. These words are not required in an implementation of the word set.

The Core word set, defined in sections 1 through 6, contains the required words and capabilities of a Standard System. The other word sets, defined in sections 7 through 17, are optional, making it possible to provide Standard Systems with tailored levels of functionality.

See: A.1.3.1 Word sets

1.3.1.1 Text sections

Within each word set, section 1 contains introductory and explanatory material and section 2 introduces terms and notation used throughout the Standard. There are no requirements in these sections.

Sections 3 and 4 contain the usage and documentation requirements, respectively, for Standard Systems and Programs, while section 5 specifies their labeling.

1.3.1.2 Glossary sections

Section 6 of each word set specifies the required behavior of the definitions in the word set and the extensions word set.

1.3.2 Annexes

The annexes do not contain any required material.

Annex A provides some of the rationale behind the committee's decisions in creating this Standard, as well as implementation examples. It has the same section numbering as the body of the Standard to make it easy to relate each requirements section to its rationale section.

Annex B is a short bibliography on Forth.

Annex C provides an introduction to Forth.

Annex D discusses the compatibility of ANS Forth with earlier Forths, emphasizing the differences from Forth-83.

Annex E presents some techniques for writing portable programs in ANS Forth.

Annex F includes the words from all word sets in a single list, and serves as an index of ANS Forth words.

1.4 Future directions

1.4.1 New technology

This Standard adopts certain words and practices that are increasingly found in common practice. New words have also been adopted to ease creation of portable programs.

1.4.2 Obsolescent features

This Standard adopts certain words and practices that cause some previously used words to become obsolescent. Although retained here because of their widespread use, their use in new implementations or new programs is discouraged, because they may be withdrawn from future revisions of the Standard.

This Standard designates the following words as obsolescent:

6.2.0060        #TIB
15.6.2.1580     FORGET
6.2.2240        SPAN
6.2.0970        CONVERT
6.2.2040        QUERY
6.2.2290        TIB
6.2.1390        EXPECT

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