P R O C E S S O R:
CENTRAL PROCESSING UNIT (CPU):
CPU is the brain of computer system. it perform major comparisons, and also activates and control the operations of other units of computer system. hence no other single component determine overall performance as much as CPU. In order to capabilities of processor it is important to know internal structure of processor.
CONTROL UNIT (CU):
The control unit of CPU select and interprets program instructions and then coordinate their execution. as above figure 1.1 shows it has special purpose registers and a decoder to perform these activates. The special purpose register named as instruction register and program control register respectively, hold the current instruction and the next instruction for execution and in this way help control unit in instruction selection.on the other hand the decoder has necessary circuitry to decode and interprets the meaning of every instruction supported by CPU.
Each instruction is accompanied by microcode —- very basic direction that tell CPU how to execute instruction. The control unit does not perform any actual processing of data, it act as CENTRAL NERVOUS SYSTEM for all other components of computer. It manage and coordinate the entire computer system including input and output units. It obtained instruction from a program stored in main memory, interprets the instruction, and issues signals that cause other units of system to execute them.
ALU of a CPU is the place where actual execution of instruction takes place during data processing. When the control unit encounters an instruction that involves(such as add, subtract, multiply, divide) it passes control to the ALU. The numbers into ALU register and then tell ALU the ALU to add them or any arithmetic operation to perform or check whether they are equal or greater or lesser(logical operation).
M I C R O P R O C E S S O R:
When entire CPU is attaches on single tiny chip it is known as microprocessor.

INSTRUCTION SET:
Instruction code: the ability to execute set of machine instruction on is known as instruction code.mostly computer have more than 200 instruction per second.CPU s made by different manufacturer have different instruction codes. In fact different CPU models of same manufacturer can have different instruction codes.when they develop new CPU they ensures that its instruction set include all instructions in instruction set of processor CPU plus new ones. This manufacturing strategy is known as backward compatibility and the new CPU is said to be backward compatible with its new processor.this feature allow software written for computer with particular CPU to work on computers with newer processors of same family.

Registers:
To handle the process satisfactorily and to to speed up rate of information transfer , the CPU uses a number of special memory units called registers. The register holds information temporarily.
Length of register is equal to number of bits it can store. However here are register of 32-bits and 64-bits.
Sr.no.
Name of register
functions

1
MAR
Hold address of active memory location

2
MBR
Hold information on its way to and from memory

3
PC
Hold address of next instruction to be executed

4
A
Accumulates results and dates to be operated upon

5
I
Hold an instruction it is being executed

6
I\O
Communicate with I\O devices

Processor speed:
Central unit and arithmetic and logical unit perform execution on incredible speed. These operation are mostly synchronized with the help of a built in electronic clock (known as system code) which emits millions of regularity speed electronic pulses per second (known a clock cycle).
A processor fetch decode execute instruction at proper interval with interval timed by specific number of clock cycles. Normally fewer cycles are required to fetch decode execute cycle. The shorter the clock cycle the faster the speed of processing. Mostly we measure the speed by following units:
1. Megahertz(MHz) which is equal to 10^6
2. Gigahertz (GHz) which is equal 10^9 over the last years the speed of processor increased steadily . most popular PCs have clock cycles speed of 500MHz(0.5GHz)to4000MHz(4.0GHz). normally we measure the speed of cycle per second but in minicomputer and mainframe computers system MIPS (million of instruction per second) or BIPS(billion of instruction per second).etc
Types of processor:
1. CISC PROCESSOR (complex instruction set computers)
2. RISC PROCESSOR( reduced instruction set computers)
3. EPIC PROCESSOR(explicitly parallel instruction computing)
4. Multicore processors
5. Power efficient processors

Summary:

Processor is brain of computer which control overall functionality of computer. Processor is small chip which is placed on motherboard and processor is made from a semiconductor (silicon). To know about processor the processor is divided into parts which are control unit and arithmetic and logical units .control unit work as a nervous system which arithmetic and logical unit perform addition subtraction etc and determine whether greater or less respectively. Hence there was still a question how can we determine which part of processor perform which function and how can we determine its speed???so on this basis they divided processor internal chips named as registers which perform their functionality and the cycle of fetch decode and execute was the unit to determine the speed.mostly PCs are determine by MHz or GHz the shorter the clock cycle the greater the speed.