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Elcomp Forth_DOS 25.atr 92.2 kB 1 29-May-2022 16:02 Andreas Tartz Elcomp Forth_DOS 25.atr
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Grafs Atari-Forth DOS 2.5.atr 92.2 kB 1 29-May-2022 16:03 Andreas Tartz Grafs Atari-Forth DOS 2.5.atr
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Grafs_Atari-Forth_DOS_2.5.atr 92.2 kB 1 29-May-2022 22:41 Roland B. Wassenberg Grafs_Atari-Forth_DOS_2.5.atr
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fig-FORTH1.4S-1.atr 92.2 kB 1 05-Jul-2016 10:53 Roland B. Wassenberg fig-FORTH1.4S-1
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fig-FORTH1.4S-2.atr 92.2 kB 1 05-Jul-2016 10:53 Roland B. Wassenberg fig-FORTH1.4S-2

This page (revision-80) was last changed on 09-Jun-2022 08:00 by Carsten Strotmann  

This page was created on 20-Feb-2010 21:56 by Carsten Strotmann

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At line 6 changed one line
Forth is an interpreted programming language that uses a stack-based metaphor in an effort to reduce memory requirements as much as possible. It is perhaps the only successful example of such a language; the PostScript system was derived from it and saw much widespread use, but this was hidden inside the printers and not seen by end-users or programmers.
Forth is a cancatenative stack-based programming language.
At line 8 changed one line
Stack-based languages simplify the interpreter's parser considerably because the data for an instruction always appears in the source code before the instructions that will use it. To see why this helps, consider this typical line of [Basic]:\\
Stack-based languages simplify the language's parser considerably because the data for an instruction always appears in the source code before the instructions that will use it. To see why this helps, consider this typical line of [Basic]:\\
At line 12 changed one line
To perform this line, the interpreter has to read the entire line, look up the value of B (let's say 30), realize that the * has to be performed before + and order the instructions correctly, and then finally convert those into instructions something like:\\
To perform this line, the interpreter has to read the entire line, look up the value of B (let's say 3), realize that the * has to be performed before + and order the instructions correctly, and then finally convert those into instructions something like:\\
At line 24 changed one line
When this code is performed, the interpreter pushes the value of B on the stack, then 20. It then encounters the mul, which removes the last two items, the 30 and 20, multiplies them, and puts the result back on the stack. Next, it pushes 10 on the stack, leaving the top two locations containing 60 and 10. It then encounters add, taking the two values, adding them, and putting the result back on the stack. The top of the stack now contains the result, 70.
When this code is performed, the interpreter pushes the value of B on the stack, then 20. It then encounters the mul, which removes the last two items, the 3 and 20, multiplies them, and puts the result back on the stack. Next, it pushes 10 on the stack, leaving the top two locations containing 60 and 10. It then encounters add, taking the two values, adding them, and putting the result back on the stack. The top of the stack now contains the result, 70.
At line 28 changed one line
Another key aspect of the language was Forth's inherently multitasking design. The program could set up separate stacks and feed different code into each one. The Forth kernel would run each of these stacks in turn, so all Forth programs had access to these features. This made writing multithreaded code very easy, so one could, for instance, have a thread reading the joystick as it moved, and then read that value in a game loop in another stack.
Another key aspect of the language is Forth's inherently multitasking design. The program could set up separate stacks and feed different code into each one. The Forth kernel would run each of these stacks in turn, so all Forth programs had access to these features. This made writing multithreaded code very easy, so one could, for instance, have a thread reading the joystick as it moved, and then read that value in a game loop in another stack.
At line 30 removed 4 lines
The downside to the stack-based approach is that it makes the language difficult to understand by mere mortals. Even tutorials purporting to show how simple it was often ended in an unreadable mess. As a result, Forth was subject to perhaps one of the longest running fanboi wars since APL was invented. Constantly derided by practically everyone in the industry, it saw some interest in spite of this, but little commercial software emerged. The singular exception is the PostScript system, which is essentially a version of Forth modified to produce graphics output.
The Atari 8-bits were being sold right in the middle of this battle, and as a result there was a fair amount of support on the platform and some interest in the press.
At line 58 added 3 lines
* [CoinOp FORTH]
* [Elcomp Forth_DOS 25.atr]; Atari Version of Elcomp-Forth by E.Floegel & H.C.Wagner, 1982
* [Grafs Atari-Forth DOS 2.5.atr|Grafs_Atari-Forth_DOS_2.5.atr]; from Andreas Graf ca. 1990
At line 62 added 5 lines
!! Forth Books
* [Using Fig FORTH On The Atari 800 By Stephen A. Cohen|https://archive.org/details/UsingFigFORTHOnTheAtari800ByStephenACohen]
* [APX 20157 FORTH Turtle Graphics Plus Manual by William D. Volk|https://archive.org/details/APX20157FORTHTurtleGraphicsPlusManual]
Version Date Modified Size Author Changes ... Change note
80 09-Jun-2022 08:00 6.129 kB Carsten Strotmann to previous
79 29-May-2022 22:48 7.176 kB Roland B. Wassenberg to previous | to last
78 29-May-2022 22:42 7.239 kB Roland B. Wassenberg to previous | to last
77 29-May-2022 22:36 7.209 kB Roland B. Wassenberg to previous | to last
76 29-May-2022 16:22 7.146 kB Andreas Tartz to previous | to last
75 13-Sep-2021 05:48 6.991 kB Robert Roland to previous | to last
74 13-Sep-2021 05:40 6.709 kB Robert Roland to previous | to last
73 31-Mar-2021 19:38 6.691 kB Roland B. Wassenberg to previous | to last
72 01-May-2018 03:30 6.695 kB Roland B. Wassenberg to previous | to last
71 28-Apr-2018 15:44 6.695 kB Maury Markowitz to previous | to last
70 28-Apr-2018 15:38 6.295 kB Maury Markowitz to previous | to last
69 28-Apr-2018 15:36 6.27 kB Maury Markowitz to previous | to last
68 26-Apr-2018 22:31 4.923 kB Maury Markowitz to previous | to last
67 26-Apr-2018 22:19 4.336 kB Maury Markowitz to previous | to last
66 29-Aug-2017 04:50 3.271 kB Roland B. Wassenberg to previous | to last
65 25-Feb-2017 16:55 3.292 kB Carsten Strotmann to previous | to last
64 05-Jul-2016 10:56 3.153 kB Roland B. Wassenberg to previous | to last
63 02-Jul-2016 01:07 3.103 kB Roland B. Wassenberg to previous | to last
62 01-Jul-2016 18:40 3.062 kB Roland B. Wassenberg to previous | to last
61 23-Jan-2014 18:28 3.048 kB Carsten Strotmann to previous | to last
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