# ALU

**Analog Value**

Analog quantity has continuous values.Most of the things in nature appear in analog form. Temperature never goes from 30 to 31 instantly.It takes infinite steps. If we draw a graphical representation, it will give us a continuous curve waveform.

**Digital Value**

Digital quantity has discrete values.It takes finite steps. If we draw a graphical representation, it will give us a discrete waveform.

- Digital data can be processed efficiently.
- Can be stored easily due to limited amount of information.
- Noise does not affect digital data.
- digital circuits consume low power.

**Machine Language**

A system of codes directly understandable by a computer’s CPU is termed as machine language. Machine language is composed only of the two binary digits 0 and 1.

### Compiler/Interpreter.

It is a software that converts the programming language into machine language.

**Bit**

It is the minimum information that can be handled by a computer. It is not an imaginary thing, it exists physically in the form of voltage levels.In computer circuitry, a bit is represented by voltage levels which are assigned on the basis of circuit type.

### Base 2 Number system

- 02 symbols (0,1)
- Computer only recognize off and on like a light switch.
- Instructions and data are composed of only a series of bits.
- a single bit is represented by a small “b” and a byte is represented by a capital “B”.
- Four(04) bits form a nybble.
- Eight(08) bits form a single byte.
- In computer, we use byte structure to store data.

Computer handles a series of binary numbers (1010100011011011 or on/off) in two forms

- Data
- Set of Instructions

Both of these sets are handle by CPU.This on and Off instructions are known as bits.

**Bit**

bit is the minimum information that can be handled by a computer

### Arithmetic Logic Unit

The Arithmetic Logic Unit [ALU] performs arithmetic (Addition, Multiplication etc) and logic operations (AND, OR, COMPLEMENT, EX-OR etc) on binary data which is stored in internal registers.Three basic logic operations are

- AND
- OR
- NOT

### Logic Gate:

A circuit that performs a logic operation is called a logic gate. Basic logic elements can combined to form complex logic circuits to perform useful operations like, Comparison, code conversion, encoding, decoding, storage, counting and etc…

### AND Gate

AND gate produce high output if, all inputs are high.If any one of them is low then it will produce low level voltage.

### OR Gate

OR gate produce high output if, any one of the input is high.If both inputs are low then it will produce low output voltage level.

### NOT Gate

NOT gate inverts the logic level.

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