FreeCalypso > hg > ueda-linux

annotate ueda/doc/uschemlang.txt @ 81:6e43956e740d

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
beginning of BOM utils refactoring: seqrefdes code factored out
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 23 Feb 2017 19:15:48 +0000
parents cd92449fdb51
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
0
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
1 uschem language for schematic sheets
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
2
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
3 uschem is the component of uEDA that deals with the graphical or non-graphical
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
4 schematic sheets as opposed to the MCL. These schematic sheets are ASCII text
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
5 files (conventional suffix is .usch, although it isn't hard-coded into any uEDA
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
6 tools) in a special language defined in this document.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
7
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
8 At the high level each schematic sheet may be either graphical or non-graphical
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
9 and consists of a set of objects that embody electrical and/or graphical
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
10 information. Component objects (component instances) provide a link between the
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
11 schematic sheet and the MCL, Net and GraphNet objects declare electrical
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
12 interconnections (see netlisting.txt), GraphBlock objects serve as containers
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
13 for purely graphical elements, and a few other object types will be explained in
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
14 detail later. Most object types accept decorations, which are the uschem
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
15 syntactic term for information elements that are not objects in themselves, but
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
16 are attached to a particular object.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
17
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
18 At the low level the uschem syntax is based on the same principle as C and many
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
19 other languages used in the UNIX world: the source file is treated as consisting
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
20 of tokens which are either self-delimiting or delimited by white space; with a
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
21 few exceptions all white space (spaces, tabs and newlines) is treated the same,
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
22 i.e., line boundaries have no special significance to the parser. The tokens
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
23 which make up the language consist of:
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
24
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
25 * ASCII characters (),;={} are self-delimiting tokens.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
26
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
27 * A quoted string (enclosed in double quotes '"') is a quoted-string token.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
28 To include a '"' character in a quoted string, escape it as '\"'; to include
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
29 a backslash '\', escape it as '\\'.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
30
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
31 * The following tokens are delimited by white space, by any of the self-
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
32 delimiting tokens listed above, or by '%' comments (see below):
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
33
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
34 + Keywords
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
35 + Numbers (decimal integers)
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
36 + Any other strings (unquoted-string tokens)
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
37
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
38 Wherever the syntax calls for a string giving some user data, either a quoted or
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
39 an unquoted string may be given; quoted strings are required only if they
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
40 contain special characters. Keywords and numbers must not be quoted.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
41
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
42 Comments
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
43
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
44 The uschem language supports two kinds of comments. The first kind are
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
45 PostScript-style comments. These comments are introduced by a '%' character and
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
46 continue to the end of the line (one of the few places in the uschem language
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
47 where newlines differ from other white space). This comment style is very
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
48 convenient, but they suffer from one serious problem: if a schematic sheet is
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
49 processed by a program that parses the original, does some transformations to
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
50 it, and writes out a new .usch file (uschem-rewrite(1) or the future graphical
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
51 schematic editor), PostScript-style comments will be lost because they are not
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
52 structured and thus cannot survive the parsing process.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
53
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
54 The other kind of comments are structured comments. These take the form of
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
55 Comment objects or Comment decorations on other objects; the body of the comment
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
56 takes the form of a string token (usually quoted). Because they take their
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
57 proper place in the uschem language of objects and decorations, such structured
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
58 comments can survive processing by tools that manipulate schematic sheets at
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
59 that level.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
60
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
61 Graphics model
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
62
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
63 The graphical aspects of uschem schematics have been borrowed heavily from
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
64 gschem, the schematic capture tool from the gEDA project - the latter is the
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
65 closest thing to a mainstream EDA package that has ever been used by the author
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
66 of uEDA. All geometric dimensions for graphical elements on schematic sheets as
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
67 well as the dimensions of the sheets themselves are given in gschem units, and
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
68 most of the commonly used graphics primitives have also been copied from gschem.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
69 Users wanting to make use of the graphical features of uschem need to be
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
70 familiar with gschem as these gschem-derived graphical features won't be
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
71 described here in detail.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
72
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
73 There is, however, one major difference between the graphics models of gschem
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
74 and uschem. gschem is a GUI application and its graphics primitives are
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
75 intended primarily for on-screen display and editing; gschem supports PostScript
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
76 output as an afterthought. uschem on the other hand is designed with the
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
77 philosophy that PostScript is the canonical and authoritative representation of
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
78 a graphical schematic sheet; whatever form is used to represent graphical
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
79 elements in the source code, the assumption is that they are all ultimately
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
80 destined to become PostScript.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
81
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
82 Graphical elements emitted into the PostScript output by uschem-print(1) come
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
83 from the following sources:
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
84
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
85 * GraphBlock structures (objects or decorations) which are containers for purely
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
86 graphical elements in schematic sheets;
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
87
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
88 * Graphical symbols pulled from the library to represent component instances as
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
89 well as for other purposes - see graphsyms.txt;
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
90
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
91 * Text emitted by DisplayAttr and DisplayNetName decorations;
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
92
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
93 * Lines drawn for GraphNet, NetLine and BusSeg objects.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
94
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
95 GraphBlock structures may be of two forms: GraphBlockG and GraphBlockPS. The
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
96 former contain gschem code, the latter contain PostScript code. PostScript is
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
97 the native form; gschem code is printed by turning it into PostScript, hence
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
98 GraphBlockPS can do everything that GraphBlockG can plus much more. GraphBlockG
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
99 should be considered a backward compatibility feature. A similar situation
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
100 exists with graphical symbols as described more fully in graphsyms.txt.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
101
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
102 See psfeatures.txt for the information you need to know in order to write
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
103 PostScript code for inclusion into GraphBlockPS structures or symbols.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
104
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
105 Coordinate system
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
106
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
107 As already noted earlier, all graphical coordinates are given in gschem units.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
108 Analogously to both gschem and PostScript default the origin of the coordinate
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
109 system is in the lower left corner; x coordinates increase to the right and y
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
110 coordinates increase upward. There is, however, one subtle difference between
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
111 gschem and uschem coordinate systems. In gschem schematic sheets the absolute
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
112 coordinates are essentially arbitrary and one needs to use a special titleblock
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
113 "component" to set the overall dimensions of the drawing sheet; the coordinates
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
114 that really matter then need to be calculated relative to the arbitrary ones of
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
115 that titleblock component. uschem has done away with such silliness and every
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
116 graphical schematic sheet in the uschem language begins with an explicit size
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
117 declaration.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
118
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
119 The sheet size declaration given at the beginning of a uschem sheet sets the
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
120 effective limits for the coordinate system, but it does not cause any border or
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
121 title block to be drawn. If such features are desired (they normally are), they
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
122 need to be embodied in a GraphBlock object.
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
123
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
124 One gschem misfeature that has unfortunately been retained in uschem is the
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
125 fictitious nature of the drawing sizes. Using gschem and following the size
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
126 conventions set for its standard symbol library, one has to declare the drawing
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
127 as having size D (use title-D.sym) in order to make it reasonable for printing
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
128 in size B; this situation unfortunately remains in uschem. The sheet size
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
129 declaration merely establishes the size of the in-sheet coordinate system in the
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
130 fake gschem units, whereas the actual print size is given on the command line to
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
131 uschem-print(1). uschem's PostScript prolog code calculates and effects the
cd92449fdb51 initial import of ueda and ifctf-part-lib from ifctfvax CVS
Space Falcon <falcon@ivan.Harhan.ORG>
parents:
diff changeset
132 necessary scaling.