Chapter VI: ADVANCED EDITING

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Creation Defaults

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The Duplicate command is useful because a node may have been modified (rotated, scaled, etc.) and duplication preserves all of those changes. Another way to create nodes that are nonstandard is to set creation defaults.

The Set Node Defaults... command of the Info menu provides a dialog for changing this information on subsequently created nodes. Defaults can be set for primitive nodes in the current technology or for facet instances in the current library. For primitives, it is possible to set their default size and orientation (rotation/transposition). For facet instances, it is possible to set their default expansion and orientation. Note that the default unit for typed values is lambda, unless another unit is explicitly mentioned (see the Change Units... command of the Technology menu for more on lambda and units.

Figure 6.1

The special checkbox "Disallow modification of existing facets" requests that all facet instances be anchored. Any command that results in the movement of a facet instance will fail. This is useful when a large circuit is being assembled, for it is often the case that there are many facet instances that must be wired together. It is common during this phase of design to accidentally create, delete, move, or otherwise alter the facets, which causes an annoying delay in editing. This checkbox prevents the placement from being affected by wire editing commands. Wires may still be created, and primitives may still be fully edited, but any attempt to manipulate facet instances results in an error.

The check box "Disallow modification of locked primitives" requests that all lockable primitive node instances be anchored. Like the facet modification lock, these nodes cannot be created, deleted, or modified in any way while the lock is on. Typically, only primitives in "array" technologies are lockable, presuming that these components will be used to define the fixed circuitry that is then customized. Design of the fixed circuitry can be done with this lock off, and then the customization phase can be done with this lock on.

The check box "Tiny facets hashed out" requests that facets be displayed with a gray hash pattern when they are too tiny for their contents to be distinguished. Without this option, all geometry is drawn, which can take a long time.

The other special check box in the defaults dialog is "Check facet dates during creation" which requests that date information be used to ensure a proper circuit building sequence. When this box is checked, warning messages will be issued when editing a facet that has more recent subfacet instances. Electric tracks facet creation and revision dates, and this information can be displayed with the List Facet Dates command of the Info menu.


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