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<TITLE>Magic-7.3 Command Reference</TITLE>
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<H1> <IMG SRC=graphics/magic_title2.gif ALT="Magic VLSI Layout Tool Version 7.3">
<IMG SRC=graphics/magic_OGL_sm.gif ALIGN="top" ALT="*"> </H1>
<H2>snap</H2>
<HR>
Cause box to snap to the selected grid when moved by the cursor. Also,
cause distance measurements to be interpreted by default as measurments
in the selected grid.
<HR>
<H3>Usage:</H3>
<BLOCKQUOTE>
<B>snap</B> [<B>internal</B>|<B>lambda</B>|<B>user</B>] <BR><BR>
</BLOCKQUOTE>
<H3>Summary:</H3>
<BLOCKQUOTE>
The <B>snap</B> command causes the cursor box to snap to the
selected grid when moved by pointer button events. The selected
grids are <B>internal</B>, the size of the internal database,
<B>lambda</B>, the lambda grid based on the technology minimum
feature size, and <B>user</B>, based on the value given by the
user to the <B>grid</B> command. <P>
In addition to changing the behavior of the box to mouse
button events, the <B>snap</B> command also changes the way
that <A HREF=distance.html>distance measurements</A> are
interpreted in commands that take distance arguments, such
as <B>move</B>, <B>copy</B>, and <B>stretch</B>. An integer
number with no other identifying units is interpreted as a
measurement in the current snap grid. All other measurements
must have an identifying unit: <B>i</B> for internal units,
<B>l</B> for lambda units, and <B>g</B> for user grid units
(as well as the usual metric units). Even when <B>snap</B>
is set to the larger lambda or user grids, it is possible to
move the cursor box to finer grid positions from the command
line. See the reference page on
<A HREF=distance.html>distance measures</A> for a complete
description of distance values. <P>
<B>snap</B> with no arguments returns the current snap grid
type. <P>
By default, the internal and lambda grids are the same. However,
CIF, GDS, or LEF/DEF input on a finer scale can cause the internal
grid to be set finer than the lambda grid. Also, the <B>scalegrid</B>
command can be used to separate the internal and lambda grids.
Note that the use of "lambda" is merely a convention. Traditionally,
scalable CMOS rules were based on units of "lambda", equal to
one-half the minimum feature size of the technology. Many
technology files are still based on lambda rules, which are usually
more conservative than vendor rules. However, some technology files
may be based on exactly implementing vendor rules, and may set
the internal grid spacing to a finer resolution, such as 0.1 micron
or smaller. In such cases, the use of the term "lambda" is a
misnomer.
</BLOCKQUOTE>
<H3>Implementation Notes:</H3>
<BLOCKQUOTE>
<B>snap</B> is implemented as a built-in command in <B>magic</B>.
</BLOCKQUOTE>
<H3>See Also:</H3>
<BLOCKQUOTE>
<A HREF=grid.html><B>grid</B></A> <BR>
</BLOCKQUOTE>
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<TD> <A HREF=commands.html>Return to command index</A>
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<P><I>Last updated:</I> October 8, 2004 at 7:16am <P>
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