Chapter 3: Hierarchy
3-9: Libraries
3-9-1: Introduction to Libraries

A library is a collection of cells 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 sometimes affects commands that work at the library level. When there are multiple libraries, you can switch between them with the Change Current Library... command (in menu File) or by using the library's context menu in the cell explorer (see Section 4-5-2). To see which libraries are read in, use the List Libraries command.

To create a new, empty library, use the New Library... command (in menu File). To change the name of the current library, use the Rename Library... command. To delete a library, use the Close Library command. This removes only the memory representation, not the disk file.

It is possible to link two libraries by placing an instance of a cell from one library into another (this is done with the Place Cell Instance... command in menu Cell). When this happens, the library with the instance (the main library) is linked to the library with the actual cell (this is the reference library). Because the reference library is needed to complete the main library, it will be read whenever the main library is read.

When there are many libraries used in the design of a circuit, it may be the case that a consistent set of library files is read into Electric, but that there are unused library files that have not been read. To detect this situation, use the Find Unused Library Files (in menu File / Check Libraries). This command will look for unused library files in the disk directories used by the circuit and will report them to you so that the disk can be cleaned-up. The command does not delete the library files: that is left to the user.

If referenced libraries are edited independently, it is possible that a reference to a cell in another library will not match the actual cell in that library. When this happens, Electric creates a "placeholder" cell that matches the original specification. Thus, the link to the referenced library is broken because the cell there does not fit where the instance should be. To see a list of all placeholder cells that were created because of such problems, use the General Cell Lists... command (in menu Cell / Cell Info) and select "Only placeholder cells".

Electric comes with some built-in libraries:

Additional libraries are available at the Static Free Software website (

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