The simplest kind of latch is the SR latch (sometimes called an SR flip flop). The S stands for Set and the R stands for Reset. If you assert the S input the Q output will assert.

Propagation delays are usually measured from the 50% amplitude points, as shown in Figure 6.3. Setup and Hold Time In Figure 6.4 below , a standard D type flip-flop (e.g., a 74xx74 device) is shown ...