81 lines
2.1 KiB
Groff
81 lines
2.1 KiB
Groff
.\" sccsid @(#)net.5 4.1 MAGIC (Berkeley) 11/29/85
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.\"
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.\" CONVENTIONS:
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.\" italics: things that are substituted for
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.\" boldface: characters that are typed as-is
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.\"
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.\" EXAMPLE: \fIfilename\fB.mag\fR
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.\" or: \fBcif \fR[\fIfile\fR]
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.\"
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.TH NET 5
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.UC 4
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.SH NAME
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net \- format of .net files read/written by Magic's netlist editor
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.SH DESCRIPTION
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.PP
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Netlist files are read and written by Magic's netlist editor
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in a very simple ASCII format.
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The first line contains
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the characters ``\ \ Netlist File'' (the leading blank is
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important).
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After that comes a blank line and then
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the descriptions of one or
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more nets.
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Each net contains one or more lines, where each
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line contains a single terminal name.
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The nets are separated
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by blank lines.
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Any line that is blank or whose first character
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is blank is considered to be a separator line and the rest of its
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contents are ignored.
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.PP
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Each terminal name is a path, much like a file path name in Unix.
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It consists of one or more fields separated by slashes.
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The last
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field in the path is the name of a label in a cell.
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The other
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fields (if any), are cell instance identifiers that form a path
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from the edit cell down to the label.
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The first instance identifier
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must name a subcell of the edit cell, the second must be a subcell
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of the first, and so on.
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.PP
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Instance identifiers are unique within their parent cells, so a
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terminal path selects a unique cell to contain the label.
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However,
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the same label may appear multiple times within its cell.
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When
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this occurs, Magic assumes that the identical labels identify
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electrically equivalent terminals; it will choose the closest of them
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when routing to that terminal.
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Further, after connecting to one of these
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terminals Magic may take advantage of the internal wiring connecting them
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together and route through a cell to complete the net's wiring.
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.PP
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An example netlist file follows below.
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It contains three distinct nets.
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.nf
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.cs R 22
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\l'10c\&\(em'
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.RS
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Netlist File
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alu/bit_1/cout
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alu/bit_2/cin
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regcell[21,2]/output
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latch[2]/input
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This line starts with a blank, so it's a separator.
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opcode_pla/out6
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shifter/drivers/shift2
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.RE
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\l'10c\&\(em'
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.cs R
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.fi
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.SH "SEE ALSO"
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magic\|(1)
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