In digital circuit theory, combinatorial logic (also called combinational logic) is a type of logic circuit whose output is a function of only the present input. This is in contrast to sequential logic, in which the output depends not only on the present input but also on the history of the input.
In other words, sequential logic has memory while combinatorial logic does not.
Combinatorial logic is used in computer circuits to do boolean algebra on input signals and on stored data. Practical computer circuits normally contain a mixture of combinatorial and sequential logic. For example, the part of an arithmetic logic unit, or ALU, that does mathematical calculations is made from combinatorial logic, although the ALU is controlled by a sequencer that is made from sequential logic.
PASS transistors are used to reduce the layout complexity of logic circuits by using PASS transistors connected to pass a first and second input function to an output node in response to selected control signals, thereby to generate a selected output function on the output node.
A logic circuit in accordance with claim 1 in which the carry output therefrom, C.sub.i, is supplied in the form of C.sub.i+1 and C.sub.i+1 as input functions in the PASS logic circuitry to produce an output S.sub.i representing the sum of the full carry adder.
The iterative combinational array is a class of combinationallogic for which the area of one circuit configuration versus another may easily be compared.
There are numerous uses to be made of combination selections such as arranging duty rotation rosters of a selected number of shift workers from an available field of eligible workers, so as to ensure fair rotation of the workers in a shift or in statistical research selecting sets of subjects from a large population.
Entering all combinations of six numbers from a chosen field of 12 numbers gives the guarantee that when all six winning numbers are among the chosen twelve, the highest prize will be awarded along with many other cash prizes.
While the foregoing enunciated method may be used for combining integers of different types as previously referred to, in the preferred embodiment the integers comprise numbers, generally of one or two digits, generally selected from an overall range of limited, predetermined extent.
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