ALU(Arithmetic and Logic Unit):

 ALU(Arithmetic and Logic Unit):

                                                                         ALU is a part of CPU. Actual execution of instruction takes places in this parts. All arithmetic and logical operations are performed in ALU.

 

• Arithmetic Unit                  Arithmetic unit of ALU performed basic arithmetic function such as addition/ subtraction / multiplication and division.
• Logic Unit                           Logic unit ALU performs logical operation like comparing two data items to find which data item is greater than equal to or less than the other.
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Control:

1.            control unit is an important components of CPU. it acts like a supervisor of the computer. it doses not execute program instruction by itself. it controls and coordinates all activities of computer system. it performs this task by using necessary commands to different components of computer. important operates performed by control unit are as follow;
2. it fetches instruction form the main memory.
3. it interprets the instruction to find what operation is to be performed.
4. it controls the execution of instruction.

Machine Cycle:

1.                          machine cycle is the sequence of actions performed by the processor to execute each instruction. The four steps of machine cycle are fetch decode execute and store
2. Fetch        instruction fetch is a process of getting an instruction from the memory to execute it.
3. Decode     The control unit decode the instruction. this process examines the nature of to move the require data form memory to ALU.
4. Execute      After decoding the instruction and getting and require data CPU finally execute the instruction. 
5. Storing        The process of writing the result to the memory is called storing.

These four operation collectively are called a machine cycle or instruction cycle. The time required to fetch and decode instruction is called instruction time or i-time

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Instruction Set:

                                  A set bits that tells a computer to perform a specific task is called instruction or instruction code. The instruction are loaded into main memory. CPU fetches instruction form memory to execute. The set of all instruction provides by the CPU is called instruction set.

Types of Instruction:

                                             The modern computer support different types of instruction as follow;

Data Transfer Instruction:

                                                         The data transfer instruction are used to transfer data form one location to other location in the computer. The data is commonly transferred the registers or between registers and memory. 

MOV(Move)                it is used transfer data from memory to register/ register to memory and register to register . it is also used to store the result of a calculation. For example the following instruction will move the value of register A.

LD(Load)                      it is used to load a register with the contain form the memory. For example the following instruction will load 25 in register A.

XCHG(Exchange)         it is used to exchange the values of two register. For example the following instruction will exchange the values of CX and BX.  

                        Data processing instructions:

                

                     coming soon......................