An investigation of the hazards in fundamental mode sequential circuit implementation using SSI, MSI and LSI devices

An extensive investigation of the essential hazard in a fundamental mode circuit was conducted using random logic. This hazard does not always exist in the circuit when it is analyzed using Unger's method. A theoretical method of detecting essential hazard was derived, and an experiment was conducted to measure the minimum delay time that would cause hazards.

The combinational part of the fundamental mode circuit was replaced by three different types of MSI and LSI devices. They are digital multiplexer, read only memory and programmable logic array. These circuits were connected to an input sequence generator which was either a microcomputer or a high frequency circuit at 909 KHz. Use of a logic analyzer allowed investigation of the combinational hazards in the MSI circuit. Sequential hazards were also considered and tested. Some possible methods of eliminating hazards in the circuit were established.

In addition, some hazards that might occur when power was turned on were also studied. Two methods of solving the power reset problem were presented, and they were applied in the experiment.