V5N3 - Complang

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FORTH Dimenstons r-example-, r-i CONTEXT I I ------ I t -A -A -- -- -- 87 NEWWORE I LINK I etc. latest word in NEWVOC vocabulary -I I I I I I I I I ~~ r-----3 I t I I C4 VOCS 1 LINK 1 BDCFA(s) 1 81 A0 I GRAFT I VOC-LINK VOC3 words not shown i I 84 VOC2 I LINK I BDCFA(s) I 81 A0 I GRAFT I VOC-LINK latest word in VOCl vocabulary t I 84 VOCl I LINK I BDCFAb) I 81 A0 I GRAFT I VOC-LINK ASSEMBLER words not shown I C5 FORTH I LINK 1 BDCFAk) I 81 A0 I GRAFT I VOC-LINK I 1 t I ,I, LIT I 00 I etc. Llateet word In FORTH vocabulary I Detailed Structure of Example Vocabulary Tree Figure Three A 6 VolurneV, NO 3
NEWVOG 1 ASCII of the new word’s name. High bit of last character will be set, with very occasional machinedepend- ent variations, e.g., on 6502 systems. 1 LINK I Link back to name field address of the previous word defined in the cur- rent vocabulary, i.e., the vocabulary in which the word NEWVOC is defined. All normal so far. The < BUILDS. . . DOES> code field address(es). This field is generally four bytes long, though the shorter, faster two-byte renderings are gaining pro- minence. This need not concern us now. You can tell how long this field is by looking for 81 A0 which will follow it. 181 7 1 This is how AOSlH, will show up in the dictionary. It is a Dummy Name Field with name of length one (the 1 in 81) and actual ASCII name 20 with high bit set, to become AO. (ASCII 20H is a blank, which was chosen be- cause it was rather unlikely to occur as an actual name in a working system. Back to this in a moment.) IGRAFT 1 It’s not clear if this field has another name, but calling it the Graft Field is useful for the moment, as this field helps in “grafting” the new vocabulary onto the vocabulary tree. The Graft Field in a vocabulary-name word like NEWVOC or FORTH is the actual field that is pointed to when we say some- thing like, “CONTEXT points to NEW- voc.” Right after NEWVOC is defined, the Graft Field of NEWVOC points to the Dummy Header Field of the vocabulary in which it was defined. In the tree Volume V, No. 3 in Figure One, for example, NEWC was defined in the vocabulary VOC2. This is caused by the action of the
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Page 3 and 4: FORTH Dimensions Published by FORTH
Page 5: FIG-Forth Vocabulary Structure Evan
Page 9 and 10: Dummy Name Field. What it finds in-
Page 11 and 12: An Easy Directory System Will Baden
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Page 23 and 24: Code and Colon Compatibility David
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Page 27 and 28: Forth183: A Minority Glenn S. Tenne
Page 29 and 30: Letters (Continued from page 4) 808
Page 31 and 32: Techniques Tutorial Meta Compiling
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Page 37 and 38: MISSOURI Kansas City Chapter Call T
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