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tutorials:forth [2022/01/06 09:29] papa [Primitive Dictionary] |
tutorials:forth [2022/03/07 16:39] lars Update to reflect this is mostly for FORTH-10. |
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- | **FORTH-10** | + | [[http:// |
- | @FORTH | + | There are two Forth implementation available. |
- | MIDAS assembly language source is available in file '' | + | **FORTH-10** is a Forth language interpreter included in the Panda TOPS-20 distribution. The anonymous programmer describes the implementation as "NOT totally standard" |
+ | |||
+ | **FORTH** is another interpreter originally written on the MIT AI lab DEC-20 called OZ, by John Wilson. | ||
+ | |||
+ | ====== Survival Guide ====== | ||
+ | |||
+ | Start the interpreter on TWENEX with the command '' | ||
+ | |||
+ | @FORTH-10 | ||
+ | FORTH-10 | ||
+ | Ok | ||
+ | |||
+ | Exit FORTH-10 with the command '' | ||
+ | |||
+ | At the '' | ||
+ | |||
+ | 7 3 Ok ( Push 7 then 3 on stack. ) | ||
+ | + Ok ( Remove two items from stack (3 and 7), push the sum on stack, so 10 is only item. ) | ||
+ | .10 Ok ( Word . pops top stack item and prints it. Stack is now empty. ) | ||
+ | |||
+ | Words '' | ||
+ | |||
+ | 3.14159 Ok | ||
+ | f.3.14159 Ok ( f. pops stack and displays as floating-point. ) | ||
+ | |||
+ | Add new words to the dictionary with the defining words '':'' | ||
+ | |||
+ | '':'' | ||
+ | |||
+ | For example, | ||
+ | |||
+ | : TIMES5 5 * ; Ok ( Define word TIMES5: Push 5 on stack (previous top value pushed lower), pop 5 and ) | ||
+ | ( previous top value, multiply and push product on stack. | ||
+ | 7 TIMES5 Ok ( Execute the word. ) | ||
+ | .35 Ok ( Pop and display result. ) | ||
+ | |||
+ | List words currently defined in the dictionary with '' | ||
+ | |||
+ | In general, Forth programs keep intermediate results on the stack instead of using variables like other languages. Words are provided to manipulate values on the stack so that they can be used in multiple procedures in the correct order. | ||
+ | |||
+ | |DROP|Pop stack without printing (discards top value).| | ||
+ | |DUP|Copy top value and push it to stack.| | ||
+ | |SWAP|Exchange the top two stack values.| | ||
+ | |ROT|Rotate top three values on stack: [1 2 3] -> [2 3 1]| | ||
+ | |OVER|Copy second item on stack and push it to top: [1 2] -> [1 2 1]| | ||
+ | |||
+ | Forth source files can be prepared with any editor. Load and interpret source files in FORTH-10 with the command '' | ||
+ | |||
+ | ====== Hello, World! ====== | ||
+ | |||
+ | : HELLO CR ." " | ||
+ | HELLO | ||
+ | HELLO, WORLD! | ||
+ | Ok | ||
+ | |||
+ | Insert comments in Forth source code with the word '' | ||
====== Primitive Dictionary ====== | ====== Primitive Dictionary ====== | ||
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LOOP +LOOP I J IJ..N RUNT REPEAT | LOOP +LOOP I J IJ..N RUNT REPEAT | ||
ERROR [NUMBER] | ERROR [NUMBER] | ||
- | |||
- | |1|2|3|4|5|6|7|8|9| | ||
- | |[[# | ||
- | |# | ||
- | |#> | ||
- | |' | ||
- | |'# | ||
- | |(|%%^%%|0=|C@|EMIT|FLUSH|[LOAD]|QUIT|THEN| | ||
- | |(" | ||
- | |[" | ||
- | |*|; | ||
- | |+|< | ||
- | |+!|<# | ||
- | |+-|< | ||
- | |, | ||
- | |,, | ||
- | |< | ||
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At start-up, FORTH-10 searches the user's log-in directory for a file named '' | At start-up, FORTH-10 searches the user's log-in directory for a file named '' | ||
+ | |||
+ | ====== Reference ====== | ||
+ | |||
+ | //Starting FORTH// is the standard introductory text for the Forth language. | ||
+ | |||
+ | * Leo Brody, //Starting FORTH//. Forth, Inc. https:// | ||
+ |