Chapter III: HIERARCHY
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9: Libraries |
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A library is a collection of cells and facets
that forms a consistent hierarchy.
To enforce this consistency, Electric stores
an entire library in one disk file that is read or written at one time.
It is possible, however, to have multiple
libraries in Electric.
Only one library is the current one, and this
affects commands that work at the library level.
A new library can be created with the
New Library... command of the File menu.
This new library will have no facets in it.
When there are multiple libraries, you can switch
between them with the Change Current Library... command.
To delete entire libraries, use the Close Library
command of the File menu.
This removes only the memory representation, not the disk file.
Note that library changes are too vast to be
tracked by the database-change mechanism and so are not undoable.
Reading Libraries
The Open Library... command of the File menu
brings a new library into Electric from disk.
These disk files are binary encoded representations of the Electric database.
Besides Electric libraries, it is possible to read circuit
descriptions that are in other formats with the
Import command of the File menu.
Most of these commands place the data into a new library
that has the same name as the disk file.
When reading these files, it is important that
the current technology be set to the one in the file
so that proper layer conversion can be done
(use the Change Current Technology... command of the Technology menu).
These formats can be read:
- Caltech Intermediate Format (CIF) is used to describe integrated
circuit layout.
It contains no connectivity, so after the library is read, it
does not know about transistors and contacts: just layers.
Use the CIF Options... subcommand of the Foreign File Options command
to affect how CIF is read.
- Stream (GDS II) is also used to describe integrated circuit layout.
It contains no connectivity, so after the library is read, it
does not know about transistors and contacts: just layers.
Use the GDS Options... subcommand of the Foreign File Options command
to affect how GDS is read.
On Windows, it is possible to select multiple files for input.
If you do this, all of the GDS will be read into the current library.
- Electronic Design Interchange Format (EDIF) is used to describe both
schematics and layout.
Electric reads EDIF version 2 0 0.
- VHDL is a hardware description language that describes the
structure of a circuit.
When VHDL is read, it is placed into a text facets with the {vhdl} view.
- AutoCAD DXF is a solid-modeling interchange format, and so it may contain 3D
objects that cannot be read into Electric.
Nevertheless, Electric creates a library of artwork primitives as well as it can.
Use the DXF Options... subcommand of the Foreign File Options command
to affect how DXF is read.
- Standard Delay Format (SDF) is used to read test vector parameters
and place them on facets in the current library.
Before this data can be used by the simulator, one of the three sets
(Typical, Minimum, or Maximum) must be
selected with the Annotate Delay Data subcommand of the
Simulate command of the Tools menu.
- Schematic User Environment (SUE) is a schematic editor that captures
a single cell in each file.
Because of this, the circuitry in SUE files is added to the current library instead
of being placed in its own library (since many SUE files may have to be read to
build up a single Electric library).
- Readable Dump is an Electric-specific format that captures the entire
database, but in an editable text format.
Because it is a text, it is slower to read than Electric's binary files,
and takes up more space on disk.
However, it can be transferred between machines
more reliably and can be edited if necessary.
See section 7-3
for more information on external formats.
Writing Libraries
Writing libraries to disk is done with the
Save Library command of the File menu.
If the library was read from disk, it is written back to
the same file.
If, however, you wish to write the library to a new file
(thus preserving the original) then use the Save As... command.
Electric can also write external format files with the
Export command of the File menu.
These formats can be written:
- Caltech Intermediate Format (CIF) is used to describe integrated
circuit layout.
The output file contains only the current facet and any
circuitry below that in the hierarchy.
Use the CIF Options... subcommand of the Foreign File Options command
to affect how CIF is written.
- Stream (GDS II) is also used to describe integrated circuit layout.
The output file contains only the current facet and any
circuitry below that in the hierarchy.
Use the GDS Options... subcommand of the Foreign File Options command
to affect how GDS is written.
- Electronic Design Interchange Format (EDIF) can write either
the Netlist or the Schematic view of the circuit.
Use the EDIF Options... subcommand of the Foreign File Options command
to affect how EDIF is written.
Electric writes EDIF version 2 0 0.
- AutoCAD DXF is a solid-modeling interchange format.
Use the DXF Options... subcommand of the Foreign File Options command
to affect how DXF is written.
- L is the GDT language, still appearing in some commercial systems.
The output file contains only the current facet and any
circuitry below that in the hierarchy.
- PostScript is the Adobe printing language.
The output file contains only a visual representation of the current facet
(or part of that facet).
PostScript options can be controlled with the Print Options... command of the
File menu.
- HPGL is the Hewlett-Packard printing language.
The output file contains only a visual representation of the current facet
(or part of that facet).
HPGL options can be controlled with the Print Options... command of the
File menu.
- Readable Dump is an Electric-specific format that captures the entire
database, but in an editable text format.
Because it is a text, it takes up more space on disk.
However, it can be transferred between machines
more reliably and can be edited if necessary.
See section 7-3
for more information on external formats.