A depth knowledge about processor internal structure and functions

DATA I/O BUS  or  FSB(FRONT SIDE BUS):

This is an external bus of CPU used for communicate between RAM and Processor through Chipset usualy Northbridge.The Speed of FSB is Measured in MHz or GHz.The faster frontside bus lead to faster overall performance.

Control Unit or CU:

 A control unit works by receiving input information that it converts into control signals, which are then sent to the central processor. The computer's processor then tells the attached hardware what operations to carry out.

ALU or Arithmetic Logic Unit:

After Getting the control signal from CU An ALU performs basic arithmetic and logic operations. Examples of arithmetic operations are addition, subtraction, multiplication, and division. Examples of logic operations are comparisons of values such as NOT, AND, and OR.

Register:

Registers are the most important components of CPU.There have many types of register presents in a CPU.  Each register performs a specific function. A short description of most important CPU's registers and their functions are given below.

Memory Address Register (MAR): This register holds the address of memory where CPU wants to read or write data.

Memory Buffer Register (MBR): This register holds the contents of data or instruction read from, or written in memory.

I/O Address Register (I/O AR): I/O Address register is used to specify the address of a particular I/O device.

I/O Buffer Register (I/O I3R): I/O Buffer Register is used for exchanging data between the I/O module and the processor.

Program Counter (PC): Program Counter register is also known as Instruction Pointer Register. This register is used to store the address of the next instruction to be fetched for execution

Instruction Register (IR): Once an instruction is fetched from main memory, it is stored in the Instruction Register.

Accumulator Register: The accumulator register is located inside the ALU, It is used during arithmetic & logical operations of ALU.

Flag Register: The Flag register is used to indicate occurrence of a certain condition during an operation of the CPU. It is a special purpose register with size one byte or two bytes. Each bit of the flag register constitutes a flag (or alarm), such that the bit value indicates if a specified condition was encountered while executing an instruction.

Internal Data Bus 32/64:

This bus perform internal data exchange between ALU and Register.This bus has two different architechtures 32bit and 64bit. 64bit support both 64bit and 32bit Softwares.but 32bit only support 32bit O.S and Applications.

Cache Memory:

Cache memory is a small amount of high speed memory constructed using static ram. The most recently processing data is stored in cache memory. CPU can access this data more quickly than it can access data in RAM. When the microprocessor starts processing the data, it first checks in cache memory.there are 3 levels of cache memory. L1, L2, and L3. L1 storage capacity is small than L2 and L3 around (8KB -64KB) , but fastest than L2 and L3. L2 storage capacity is small than L3 around (64KB-4MB) but fast than L3. L3 not presents in all system.  it storage capacity is around 8MB.

Backside Bus:

This bus is used for connect the CPU to the Cache memory.