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.