Buffer
| Library: | Gates | ||||
| Introduced: | 2.0 Beta 1 | ||||
| Appearance: |
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Behavior
The buffer simply passes through to its right output whatever input it receives on the left side. The way data is presented on the output is defined by the output value attribute. The truth table for a one-bit buffer is the following.
| In | Out | ||
|---|---|---|---|
| O/1 | O/flt. | flt./1 | |
| 0 | 0 | 0 | U |
| 1 | 1 | U | 1 |
| U | U | U | U |
| E | E | E | E |
If the input is unspecified (i.e., floating U), then the output will also be unspecified. If the input is an error (E) value, then the output will also be.
Buffers are the most useless of the gate components provided in Logisim; its presence in the Gates library is just as much a matter of completeness (a component for each possible one-input truth table) as it is a matter of providing useful functionality. Still, it can be occasionally useful to ensure that values propagate in only one direction along a wire or to add a transmission delay.
Pins (assuming component faces east)
- West edge:
- The input into the component. Bit width according to Data Bits attribute.
- East edge:
- The output, which always matches the input into the left side. Bit width according to Data Bits attribute. The data presentation mode is defined by the Output Value attribute.
Attributes
When the component is selected or being added, Alt-0 through Alt-9 alter its Data Bits attribute and the arrow keys alter its Facing attribute.
- Facing
- The direction of the component, its output relative to input.
- Data Bits
- The bit width of the component's inputs and outputs.
- Output Value
-
By default the choice 0/1 indicates how false and true results should be translated into output values. By default, false is indicated by a low voltage (0) and true by a high voltage (1). With the 0/floting ou floating/1 choices one or the other can be replaced by a high-impedance (
floating
U) value instead. This allows wired-or and wired-and connections, as illustrated in the AND/OR/NAND/NOR Gate documentation. - Label
- The text within the label associated with the gate.
- Label Font
- The font with which to render the label.
Poke Tool Behavior
None.
Text Tool Behavior
Allows the label associated with the gate to be edited.
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