# Computer Awareness Study Notes on Arithmetic and Logic Unit (ALU)

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1553            Computer Awareness is one of the most important subjects that come in the Banking exam. However, not many candidates pay a great deal of attention towards this particular subject.

Computers form the basis of the working any organization in today’s age. If you are looking forward to working in a bank, then you need to have a basic understanding of computers. This is exactly what this section of the exams tests you for.

Here We have listed the important of Computer Awareness Study Material for competitive exams. Here we are providing Study Notes of Computer.

## What is Arithmetic and Logic Unit (ALU) ?

In computing an Arithmetic logic unit (ALU) is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit (CPU) of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers. The processors found inside modern CPUs and graphics processing units (GPUs) accommodate very powerful and very complex ALUs; a single component may contain a number of ALUs.

ALU contains the logical circuit to perform mathematical operations like subtraction, addition, multiplication, division, logical operations and logical shifts on the values held in the processors registers or its accumulator.

Mathematician John von Neumann proposed the ALU concept in 1945, when he wrote a report on the foundations for a new computer called the EDVAC. Research into ALUs remains an important part of computer science, falling under Arithmetic and logic
structures in the ACM Computing Classification System.

ALU is also known as an Integer Unit (IU). The arithmetic logic unit is that part of the CPU that handles all the calculations the CPU may need. Most of these operations are logical in nature. Depending on how the ALU is designed, it can make the CPU more powerful, but it also consumes more energy and creates more heat. Therefore, there must be a balance between how powerful and complex the ALU is and how expensive the whole unit becomes. This is why faster CPUs are more expensive, consume more power and dissipate more heat.

### Fundamental attributes of an ALU

The three fundamental attributes of an ALU are its operands and results, functional organization, and algorithms.

Operands and Results : The operands and results of the ALU are machine words of two kinds: arithmetic words, which represent numerical values in digital form, and logic words, which represent arbitrary sets of digitally encoded symbols. Arithmetic words consist of digit vectors (strings of digits).

Operator:Operator is arithmetic or logical operation that is performed on the operand given in instructions.

Flag: ALU uses many types of the flag during processing instructions. All these bits are stored in status or flag registers