Chapter 3: HIERARCHY


3-1: Cells


As the introductory examples showed, hierarchy is well supported in Electric. A collection of nodes and arcs is called a cell, and instances of cells can be placed in other cells. Thus, Electric still manipulates nodes and arcs, but the nodes come in two forms: primitive and complex. Primitive nodes are found in the component menu and are pre-defined by the technologies. Complex nodes are actually instances of other cells, and are found in libraries.

Besides organizing cells into a hierarchy, Electric also organizes cells according to their view and version. A cell's view describes its contents (for example "layout", "schematics", "netlist", etc.) A cell's version defines its design age. The full name of a cell is:


where CELLNAME is the name of the cell, VIEW is the abbreviated name of this cell's view, and VERSION is the version number of this cell's view. When no version number is displayed, it implies that this cell is the most recent version (has the largest number). Thus, the cell "gate;2{lay}" is more recent than "gate;1{lay}" but less recent than "gate{lay}" (which must have a higher version number, probably 3).

Figure 3.12

In this example, there is a library with two cells: "gate" and "latch". In this library are cells called "latch", "latch;1{sch}", and "latch{lay}", all of which are cells of the cell called "latch". The cell "latch" has no view name and is therefore from the "unknown" view of the cell. The cell "latch{lay}" is the layout view of the cell.

To rename a cell, use the Edit Cell... command of the Cells menu, which has a rename area at the bottom of the dialog.

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