it as ordinary assembly-language program, and Forth can link to other languages this way.) Code is so compact that application-oriented utility routines can left in the system permanently, where they are immediately available either as keyboard commands or instructions in programs, and they are used in exactly the same way in either case. No linkage editing is needed, and overlays are unusual.
REFERENCES
(1) Bell, James R. Threaded code. C. ACM 16, 6 (June 1973), 370-372.
(2) Dewar, Robert B. K. Indirect threaded code. C. ACM 18, 6 (June 1975), 330-331.
FORTH DEFINITION
FORTH is the combination of an extensible programming language and interactive operating system. It forms a consistent and complete programming environment which is then extended for each application situation.
FORTH is structured to be interpreted from indirect, threaded code. This code consists of sequences of machine independent compiled parameters, each headed by a pointer to executable machine code. The user creates his own application procedures (called 'words'), from any of the existing words and/or machine assembly language. New classes of data structures or procedures may be created; these have associated interpretive aids defined in either machine code or high level form.
The user has access to a computation stack with reverse Polish conventions. Another stack is available, usually for execution control. In an interactive environment, each word contains a symbolic identifier aiding text interpretation. The user may execute or compile source text from the terminal keyboard or mass storage device. Resident words are provided for editing and accessing the data stored on mass storage devices (disk, tape).
In applications that are to run 'stand-alone', a compact cross-compiled form is used. It consists of compiled words, interpretive aids, and machine code procedures. It is non-extensible, as the symbolic identifiers are deleted from each word, and little of the usual operating system need be included.
;S W.F.R. 8/26/78
STAFF
The volunteer staffing of FORTH DIMENSIONS is a bit fluid. For this issue, our staff consisted of:
| EDITOR | JOHN JAMES | |
| CONTRIBUTORS | KIM HARRIS | |
| W.F.RAGSDALE | ||
| TYPESETTING | TOM OLSEN | |
| JOHN JAMES | ||
| ARTWORK | ANNE RAGSDALE | |
| CIRCULATION | DAVE BENGEL | |
| DATA PROCESSING | PDP-11 |
NOTES
- The second meeting of the FORTH International Standards Team will occur in Los Angeles on October 16-19. Contact FORTH Inc. for additional information.
- A partially micro-coded FORTH-like language is described in "Threaded Code for Laboratory Computers" by J.B, Phillips, M.F. Burke, and G.S. Wilson, Dept. of Chemistry, University of Arizona, Tucson, AZ 85721. The article is published in Software - Practice and Experience, Volume 8, pages 257-263. Implementation is on a HP2100. The article also describes the advantages of threaded languages for laboratory applications.
- A "form" of FORTH for the Apple and PET 6502 based computers is available from Programma Consultants, 3400 Wilshire Blvd., Los Angeles, CA 90010. We have not used these enough to review them for this issue but they have been shipped and do work. For more information write to Programma Consultants or watch future issues of FORTH DIMENSIONS.
- FORTH Inc. is looking for a programmer with some systems-level experience using FORTH or similar languages. Interested persons should contact FORTH Inc., 815 Manhattan Avenue, Manhattan Beach, California 90266, (213) 372-8493 .
