Forth Resources

The primary source of information is the home page of the Forth Interest Group
FIG is a non-profit organization devoted to the Forth language. It includes links for obtaining Forth development systems including non-commercial systems available for downloading and the web pages for vendors of commercial systems. There are also links to articles, databases, and applications.

An ANSI standard for Forth was adopted in 1994. Most modern implementations of Forth are based on the ANS-Forth standard. Earlier standards for the language were Forth-83 and Forth-79. The language was first popularized by the Forth Interest Group which made available its FIG-Forth for a large variety of processors common at the time. FIG-Forth was so widely accepted and used that it is regarded as a de facto standard. During the development of Groups32 we used the following implementations of Forth for Windows/DOS:

This is an early implementation of the Forth-83 standard for DOS. It uses the16-bit 64k address space available on the 8086. It will run in a DOS window on current computers. It is too limited to be of much current interest.
This is an excellent development system for DOS using the Intel 80x86 chips. It uses the segmented architecture of these chips to transcend the 64k limitation. It has an integrated editor and comes with a large number of utilities (including one to allows the user of expanded memory, and both hardware and software floating point support). It uses the Forth-83 standard.
This was first released prior to the ANS-Forth standard but has been updated to comply with the standard. It only runs under Windows. It includes access to Windows system commands. It was placed in the public domain by its authors Tom Zimmer and Andrew McKewan, so it can be used to distribute applications in Forth to students and colleagues.

All of these are available from the Forth Interest Group.

Old vs New:

Older versions of Forth (like most programming languages) were directed at a broad audience. In the early days of personal computing, It was assumed that many people would do some programming. The early versions of Forth were written for the DOS environment. When the power of personal computers increased, more sophisticated implementations were written to include good editors, debugging features, etc. An excellent book for beginners (which is, unfortunately, now out of print) is "Starting Forth" by Leo Brodie. It was written for the Forth-83 standard. A more advanced book by Brodie, "Thinking Forth", explores the style and psychology of programming. As an entrée to Forth programming I still recommend FPC. It provides an integrated development environment, good documentation tools,  many features and utilities. A text which goes with this version of Forth, "Real Time Forth" by Tim Hendtlass, is available for downloading from the Forth Interest Group. As the title suggests, this is directed more at hardware control applications than mathematical applications - but much of the book is general. The Forth Interest group has links to books which document the language features of FPC and which provide information about its internal workings.

Modern versions of Forth (like most programming languages) are directed at professional programmers. They offer packages which implement object oriented programming, graphics, networking, etc. Some of the literature is directed at people who already are expert in Windows programming and are trying to learn how to do it in Forth.

A major commercial version of Forth is SwiftForth offered by Forth, Inc.  A reasonably priced system is available for purchase. A trial use version is available. Forth Inc. publishes a workbook for their course "Forth Application Techniques" as well as a "Programmers Handbook" and a "Reference Manual". Their licensing arrangement permits their system to be distributed as a platform for Forth applications provided that "the compiler and assembler or other programming aids are not available to any user of the application software".

Scientific Computing

My own work is directed at abstract algebra. There is also a body of work directed at scientific computing which exploits the floating point capabilities of Forth. Prof. Julian V. Noble of the University of Virginia has done extensive work in this area. His book, Scientific Forth, explores these applications.