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A 4-bit ripple-carry adder–subtractor based on a 4-bit adder that performs two's complement on A when D = 1 to yield S = B − A. Having an n-bit adder for A and B, then S = A + B. Then, assume the numbers are in two's complement. Then to perform B − A, two's complement theory says to invert each bit of A with a NOT gate then add one.
The following is a list of CMOS 4000-series digital logic integrated circuits.In 1968, the original 4000-series was introduced by RCA.Although more recent parts are considerably faster, the 4000 devices operate over a wide power supply range (3V to 18V recommended range for "B" series) and are well suited to unregulated battery powered applications and interfacing with sensitive analogue ...
Another extension to the series is the 7416xxx variant, representing mostly the 16-bit-wide counterpart of otherwise 8-bit-wide "base" chips with the same three ending digits. Thus e.g. a "7416373" would be the 16-bit-wide equivalent of a "74373".
Figure 1: Logic diagram for a half subtractor. The half subtractors can be designed through the combinational Boolean logic circuits [2] as shown in Figure 1 and 2. The half subtractor is a combinational circuit which is used to perform subtraction of two bits.
A full adder can be viewed as a 3:2 lossy compressor: it sums three one-bit inputs and returns the result as a single two-bit number; that is, it maps 8 input values to 4 output values. (the term "compressor" instead of "counter" was introduced in [ 13 ] )Thus, for example, a binary input of 101 results in an output of 1 + 0 + 1 = 10 (decimal ...
A very early CD4029A counter IC, in 16-pin ceramic dual in-line package (DIP-16), manufactured by RCA Colorized IC die and schematics of CD4011BE NAND gateThe 4000 series was introduced as the CD4000 COS/MOS series in 1968 by RCA [1] as a lower power and more versatile alternative to the 7400 series of transistor-transistor logic (TTL) chips.
Breaking this down into more specific terms, in order to build a 4-bit carry-bypass adder, 6 full adders would be needed. The input buses would be a 4-bit A and a 4-bit B, with a carry-in (CIN) signal. The output would be a 4-bit bus X and a carry-out signal (COUT). The first two full adders would add the first two bits together.
An example of a 4-bit Kogge–Stone adder is shown in the diagram. Each vertical stage produces a "propagate" and a "generate" bit, as shown. The culminating generate bits (the carries) are produced in the last stage (vertically), and these bits are XOR'd with the initial propagate after the input (the red boxes) to produce the sum bits. E.g., the first (least-significant) sum bit is ...