90 lines
3.3 KiB
HTML
90 lines
3.3 KiB
HTML
<HTML>
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<HEAD>
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<STYLE type="text/css">
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H1 {color: black }
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H2 {color: maroon }
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H3 {color: #007090 }
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</STYLE>
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</HEAD>
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<TITLE>Magic-8.3 Command Reference</TITLE>
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<BODY BACKGROUND=graphics/blpaper.gif>
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<H1> <IMG SRC=graphics/magic_title8_3.png ALT="Magic VLSI Layout Tool Version 8.3">
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<IMG SRC=graphics/magic_OGL_sm.gif ALIGN="top" ALT="*"> </H1>
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<H2>snap</H2>
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<HR>
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Cause box to snap to the selected grid when moved by the cursor. Also,
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cause distance measurements to be interpreted by default as measurments
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in the selected grid.
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<HR>
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<H3>Usage:</H3>
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<BLOCKQUOTE>
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<B>snap</B> [<B>internal</B>|<B>lambda</B>|<B>user</B>] <BR><BR>
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</BLOCKQUOTE>
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<H3>Summary:</H3>
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<BLOCKQUOTE>
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The <B>snap</B> command causes the cursor box to snap to the
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selected grid when moved by pointer button events. The selected
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grids are <B>internal</B>, the size of the internal database,
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<B>lambda</B>, the lambda grid based on the technology minimum
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feature size, and <B>user</B>, based on the value given by the
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user to the <B>grid</B> command. <P>
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Historically, in addition to changing the behavior of the box
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to mouse button events, the <B>snap</B> command also changed
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the way that <A HREF=distance.html>distance measurements</A>
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are interpreted in commands that take distance arguments.
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This behavior remains the default for backwards compatibility.
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The <B>units</B> command overrides this behavior and allows
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<B>snap</B> to control only the box positioning behavior,
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independently of how unsuffixed values are parsed by the
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interpreter. <P>
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<B>snap</B> with no arguments returns the current snap grid
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type. <P>
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By default, the internal and lambda grids are the same. However,
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CIF, GDS, or LEF/DEF input on a finer scale can cause the internal
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grid to be set finer than the lambda grid. Also, the <B>scalegrid</B>
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command can be used to separate the internal and lambda grids.
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Note that the use of "lambda" is merely a convention. Traditionally,
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scalable CMOS rules were based on units of "lambda", equal to
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one-half the minimum feature size of the technology. Many
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technology files are still based on lambda rules, which are usually
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more conservative than vendor rules. However, some technology files
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may be based on exactly implementing vendor rules, and may set
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the internal grid spacing to a finer resolution, such as 0.1 micron
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or smaller. In such cases, the use of the term "lambda" is a
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misnomer.
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</BLOCKQUOTE>
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<H3>Implementation Notes:</H3>
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<BLOCKQUOTE>
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<B>snap</B> is implemented as a built-in command in <B>magic</B>.
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</BLOCKQUOTE>
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<H3>See Also:</H3>
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<BLOCKQUOTE>
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<A HREF=units.html><B>units</B></A> <BR>
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<A HREF=grid.html><B>grid</B></A> <BR>
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</BLOCKQUOTE>
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<P><IMG SRC=graphics/line1.gif><P>
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<TABLE BORDER=0>
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<TR>
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<TD> <A HREF=commands.html>Return to command index</A>
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</TR>
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</TABLE>
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<P><I>Last updated:</I> March 7, 2020 at 1:06pm <P>
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</BODY>
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</HTML>
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