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[Mograsim.git] / docs / model.md

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+The simulation model consists of components connected by wires.
+
+Some components consist of other components and wires. The components contained in such a component are called the subcomponents of this component.
+
+Some wires carry one bit, and some carry multiple bits.
+
+Each bit carried by a wire is one of 1, 0, U, Z, or X. These values are IEEE 1164-compilant. (We don't use H, L, or W.)  
+See https://en.wikipedia.org/wiki/IEEE_1164 for an explanation of these values.  
+Note: We also use X to denote illegal states. For example, when two components try to put different values on the D bus, the conflicting bits on the D bus will become X.
+
+The simulation model can be viewed in the Simulation view:  
+Each rectangle represents a component. Zooming in a component reveals its inner structure (if it has one).  
+The colored lines connecting these rectangles represent wires.  
+(Multiple-bit wires are displayed thicker than the single-bit wires, and always are black.  
+For single-bit wires, the color represents their current value. These colors can be configured in the Eclipse preferences. The default values are:
+
+| Bit | Color  |
+|:---:| ------ |
+| 1   | green  |
+| 0   | grey   |
+| U   | cyan   |
+| Z   | yellow |
+| X   | red    |
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