The present invention is directed to an improved method, system and
apparatus for self-testing an electronic device. A scan latch used in a
multi-cycle bus is uniquely operated to generate signal transitions
consistent with the normal operating speed of the device. This occurs
even when a normal signal transition would not otherwise occur since the
multi-cycle bus normally requires a plurality of clock pulses to create
such signal transition. The logical states of master and slave clocks
associated with test scan logic are used to automatically cause the
output of a scan latch to invert its output or switch from its previous
state at each rising edge of the slave clock that is not preceded by a
master or scan clock. This ensures transitions will appear at the output
of the latch consistent with the operating clock speed of the slave
clock, and these transitions are detected during an AC test of the device
to determine the maximum operation frequency of the device even when the
device contains an internal multi-cycle bus.