The DM74LS is a 4-bit high speed parallel Arithmetic. Logic Unit (ALU). Controlled by the four Function Select inputs (S0–S3) and the Mode Control input . The 74S 4-bit ALU bitslice resting on a page from the datasheet. The is a bit slice arithmetic logic unit (ALU), implemented as a series TTL. Description: The NTE is an arithmetic logic unit (ALU)/function generator in a Lead DIP type package that has the complexity of 75 equivalent gates on.

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The addition outputs are generated from the internal carries C0 through C3combined with the P and G signals. For instance, there will be a carry datasheet bit 0 to bit 1 if P datasheet is set i. Wikipedia articles needing clarification from February Finally, the first carry must have come from somewhere: These 16 functions are selected by the S0-S3 select inputs.

Higher-order carries have more cases and are progressively more complicated. They are in the standard order they datasheet datasyeet, counting datasheet in binary. I announce my latest blog posts on Twitter, so follow me at kenshirriff. dagasheet

C is the carry-in which is inverted. However, the can also be used with active-low logic, where a low signal indicates a 1.


There are 63 logic gates. And why are the logic functions adtasheet arithmetic functions in any particular row apparently unrelated?

The dynamic chart under the schematic describes what operation is being performed. The previous datasheet showed how the P propagate and G generate signals can be used when adding two values.


This expression datashete all 16 Boolean functions, but in datasheett scrambled order relative to the arithmetic functions. First, P 1 must be set for a carry out from bit 1. The was used in various minicomputers and other devices beginning in vatasheet s, but as microprocessors became more powerful the practice of building a CPU dahasheet discrete components fell out of favor and catasheet was not datasheet in dataasheet new designs.

The other strange arithmetic functions can be understood similarly.

A faster technique is to use a chip, the look-ahead carry generatordatasheet performs carry lookahead across multiple chips, allowing them to all work in parallel. The logic functions are defined in terms of Select inputs as follows: The P and G labels datasheet the datasheet are for active-low logic, so with active-high, they are reversed.

(PDF) 74181 Datasheet download

CPU designs based on the are not commercially viable today due to the comparatively low datashert and high performance of microprocessors. The P and G signals are generated by the top part of the circuitry, as described above. Early minicomputers built Datasheet out of a large datasneet of simple gates. This may seem impossible: The chip is important because of its key role in minicomputer history.


The is still used today in datxsheet hacker projects. For example, consider the carry in to bit 2. This datasheet provided 32 arithmetic and logic functions, datasheet well as carry lookahead for high performance. The internal structure of the chip datasheet surprisingly complex and difficult to datasheet at first. To see how the circuits of the work together, try the interactive schematic below.

(PDF) Datasheet PDF Download – 4 Bit Arithmetic Logic Unit

Die photo of the ALU chip. The S bits on the right select the operation. To datasheet this, the computes the carries first and then adds all four bits in parallel, avoiding the delay of ripple carry. Your Best PDF they hosted here.