Specifications

110 Chapter 6—Primitive Devices
Subtractor/Decrementer
The Subtractor primitive type behaves identically to the Adder type except
that a subtract or decrement operation is performed, depending upon pin
configuration.
D Flip–Flop
The D–type flip–flop is positive-edge–triggered and obeys the following
function table:
In the above table, X on the input side means Don’t Care and on the output
side means Don’t Know.
Flip–Flop Setup and Hold Times
None of the LogicWorks primitive types explicitly implement variable
setup and hold times. However, all edge–triggered primitives have an
effective setup time of 1 unit, since they always use the input signal value
existing before the current step. For example, if the data input changes at
the same time as the clock, the old data value will be used to determine the
new output value.
You can modify this effective setup time by specifying input pin delays on
either the data or clock pins. You can check for setup and hold violations
by using the simulator’s Trigger capability to watch for value changes
within a set amount of time.
S RDClockQQ/
00XX11
01XX10
10XX01
110Rises01
111Rises10
RisesRisesXXXX
LW Reference.bk Page 110 Monday, December 15, 2003 5:59 PM