niques include {threaded code}, dedicated Forth

processors, macros at various levels, or interpreters written in another language such as C. Some implementations provide real-time response, user-defined data structures, multitasking, floating-point arithmetic, and/or virtual memory.

Some Forth systems support virtual memory without specific hardware support like MMUs. However, Forth virtual memory is usually only a sort of extended data space and does not usually support executable code.

FORTH does not distinguish between operating system calls and the language. Commands relating to I/O, file systems and virtual memory are part of the same language as the words for arithmetic, memory access, loops, IF statements, and the user's application.

Many Forth systems provide user-declared "vocabularies" which allow the same word to have different meanings in different contexts. Within one vocabulary, re-defining a word causes the previous definition to be hidden from the interpreter (and therefore the compiler), but not from previous definitions.

FORTH was first used to guide the telescope at NRAO, Kitt Peak. Moore considered it to be a fourth-generation language but his operating system wouldn't let him use six letters in a program name, so FOURTH became FORTH.

Versions include fig-FORTH, FORTH 79 and FORTH 83.

FAQs. ANS Forth standard, dpANS6.

FORTH Interest Group, Box 1105, San Carlos CA 94070.

See also 51forth, F68K, cforth, E-Forth, FORML, TILE Forth.

[Leo Brodie, "Starting Forth"].

[Leo Brodie, "Thinking Forth"].

[Jack Woehr, "Forth, the New Model"].

[R.G. Loeliger, "Threaded Interpretive Languages"].

2. FOundation for Research and Technology - Hellas.

Last updated: 1997-04-16

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th implementations differ widely. Implementationniques include {threaded code}, dedicated Forthspecific

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