Timing Verification consists of validating the path delays (primary input or storage element to primary output or storage element) to be sure they are not too long or too short and checking the clock pulses to be sure they are not too wide or too narrow. The programs addressing these problems neither produce input patterns like test pattern generators nor require input patterns like traditional simulators. Several programs (described here) operate by tracing paths [P173, WO78, SA81, KA81]. One program [MC80] extends simulation into a pessimistic analyzer not dependent on test patterns.
Timing Analysis, a program described recently in [H182a], is designed to analyze the timing of large digital computers and is based, in part, on the concepts disclosed in a patented method [DO81] for determining the extreme characteristics of logic block diagrams. The output of Timing Analysis includes "slack" at each block to provide a measure of the severity of the timing problem. The program also generates standard deviations for the times so that a statistical timing design can be produced rather than a worst case approach.
