Using Electric 4-6: Colors

Chapter IV: THE DISPLAY

| ## 6: Colors |

### Electric's Color Model

The subcommands in the Color Options command of the Windows menu control the appearance of individual layers in the editing window. Before explaining these commands, it is useful to understand the distinction between overlappable and nonoverlappable layers in Electric.

On color displays, up to five of the layers can be overlappable, meaning that when they overlap each other, it is possible to see all of them. Typically, the most commonly used layers are overlappable because it is both faster to draw and clearer to distinguish. The remaining layers in a technology are nonoverlappable, meaning that when drawn, they completely obscure anything underneath. These layers typically have stipple patterns so that they do not cover all of the bits. In this way, the nonoverlappable layers can combine without obscuring the display. Since stipple patterns are slower to draw, and since nonoverlapping color does obscure, the less common layers are drawn in this style. When editing colors, the nonoverlappable layers have only one color, whereas the overlappable layers have up to 16 different colors, considering their interaction with other overlappable layers.

### Editing Colors

The first Color Options subcommand is Edit Colors..., which presents a color mixing dialog. In the upper-right corner are seven palette-selector buttons which choose a set of colors to edit. The choices are "Primaries", "Specials", or any of the five overlappable layers (in MOSIS CMOS Submicron, the default technology, these layers are Metal-1, Polysilicon-1, P-Active, Metal-2, and Metal-3).

Each palette changes the 16 color buttons at the bottom of the dialog. The "Primaries" palette lets you edit the overlappable layers and all combinations of two overlappable layers. The individual layer palettes place all 16 combinations of that overlappable layer in the color buttons. When the "Specials" palette is chosen, you can edit special colors, such as the background, grid, highlight, etc.

To edit colors, choose a set with a palette-selector button and then choose a particular color button. At the top is a mixing palette: a hue/saturation wheel and an intensity slider. Clicking in the hue/intensity/saturation area affects the current color button.

When changing the background color, note that it must contrast with both the highlight color and the inverse of the highlight color (the inverse is black in the default settings).

The "Compute from Primaries" button helps with the tedious task of defining all combinations of overlappable colors. Since there are 5 overlappable layers, it is necessary to define 32 different combinations of these colors. Instead, you can simply select the 5 overlappable colors and the background color and then use this button to compute the remaining 26 combinations.

Another command for color manipulation is Highlight Layer..., which allows you to highlight a single layer. The command changes the colors so that all other layers are dimmer (actually 20% less saturated). The selected layer is thus highlighted on the display. Choose the "None" button to restore default colors. This command works as you click in the dialog, so that you can easily preview the circuit, one layer at a time. It only works on the overlappable layers. |

The final color subcommands are Restore Default Colors, which resets all colors to the default set for the current technology, Black Background Colors which resets all colors to the default for the current technology but with a black background, and White Background Colors which resets all colors to the default for the current technology but with a white background.

### Editing Patterns

Besides editing colors, it is also possible to edit the stipple patterns associated with each layer. The Layer Pattern Options... command of the Windows menu gives you this facility. Although many layers are drawn with solid colors on a color display, they all have patterns that are used for hardcopy output. The dialog that appears with this command allows the patterns to be edited, provides a set of predefined patterns, and allows you to determine whether or not the pattern is used on the display. You also have the option of outlining stippled polygons with a solid line. |

| Previous |  |  | Table of Contents |  | Next |