Abstract
A Null convention logic system for processing NULL convention signals
is comprised of interconnected processing elements. NULL convention
signals can assume at least a first meaningful value indicating data
and a NULL value which as no data significance. Processing elements
receive a plurality of NULL convention signals and produce a meaningful
output value when the number of meaningful input data values exceeds a
threshold number. The gates assert a NULL output when all inputs are
in the NULL state. Processing elements exhibit hysteresis such that,
as the number of meaningful input values falls below the threshold
number, the element holds a meaningful output value (or non-data
non-NULL value) until all inputs are in the NULL state. The threshold
number may be less than the total number of inputs. Groups of
elements may be interconnected, and thresholds selected, to perform
logic and other processing functions asynchronously on meaningful
signal values.