This register holds a single value, whose value is emitted on the output
Q. Each time the clock input (diagrammed with a triangle on the
component's south edge) triggers according to its Trigger attribute,
the value in the register may update based on
the two inputs on the component's west edge: The upper input is called
load and the lower is called count, and they are
interpreted as follows.
|0 or z||0
||The register remains unchanged.|
|0 or z||1 or z
||The register increments.|
||The register loads the value found at the
|1||1 or z
||The register decrements.|
The range of the register's counting can be configured using the Maximum
Before Reset attribute. When the register reaches this value, the next
increment wraps the register back to 0; and if the register is at 0,
then a decrement will wrap the register around back to its maximum value.
In addition to the output Q, the component also includes a
single-bit output carry. This is 1 whenever the register is at its
maximum and the load and count inputs indicate that the
component should increment on the next step - or when the register is at 0
and the load and count inputs indicate to decrement at
the next step.
The clear input resets the register's value to 0 (all
zeroes) asynchronously; that is, as long as the clr input
is 1, the value is pinned to 0, regardless of the clock input.
- East edge, labeled Q (output, bit width matches Data Bits attribute)
- Outputs the value currently stored by the register.
- East edge, lower pin (output, bit width 1)
- Carry: When load and count indicate to increment,
this output is 1 whenever the register is at its maximum. When load
and count indicate to decrement, this output is 1 whenever the
register is at 0. At all other times, this output is 0.
- West edge, top pin (input, bit width 1)
- Load: When this is 1 while the count input is 0, the register
will load the value found at the data input at the next clock
trigger - or, if the count input happens to be 1, the register's
value will decrement.
- West edge, middle pin labeled D
(input, bit with matches Data Bits attribute)
- Data: When the clock triggers while load is 1
and count is 0, the register's value changes to the value found at
- West edge, lower pin labeled ct (input, bit width 1)
- Count: When this is 1 or unconnected, the value in the register increments
whenever the clock input is triggered - or it decrements if the load
input happens to also be 1.
- South edge, indicated with a triangle (input, bit width 1)
- Clock: At the instant that this is triggered as specified by the Trigger
attribute, the register updates as indicated by the load and
- South edge, labeled 0 (input, bit width 1)
- Clear: When 0 or undefined, this input has no effect.
As long as it is 1, the register's value is asynchronously pinned to 0. This
occurs asynchronously - that is, without regard to the current clock input
value. As long as this is 1, the other inputs have no effect.
- Data Bits
- The bit width of the value emitted by the component.
- Maximum Before Reset
- The starting value used for the pseudorandom sequence. If this is 0
(the default), then the starting value is based on the time that the current
- Configures how the clock input is interpreted. The value
indicates that the register should update its value at the instant when the
clock rises from 0 to 1. The
falling edge value indicates that it should
update at the instant the clock falls from 1 to 0.
- The text within the label associated with the component.
- Label Font
- The font with which to render the label.
Poke Tool Behavior
Clicking the register brings keyboard focus to the register
(indicated by a red rectangle), and typing hexadecimal digits will
change the value stored in the register.
Text Tool Behavior
Allows the label associated with the component to be edited.
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