Different applications require different characteristics from
the building blocks. Logic and memory applications, for example,
require elements for computation and control, as well
as the ability to store data after computation. These elements require
sufficiently fast read and write times. The read mechanism
needs to be nondestructive, i.e., the reading mechanism should
not change the stored data while reading. To store a known digital
state and maintain low sensitivity to variations in parameters
and operating conditions, it is crucial that the stored data be
distinct, i.e., the difference between different data must be sufficiently
large. The transient power consumption while reading
and writing, as well as static power consumption, are also critical
issues.