Data processing required Input -> Processing -> Output.
In computer, CPU (Central Processing Unit) is bounded for processing using some
series of steps of a “Control Unit” and “Arithmetic and Logical Unit”.
Programs or instructions are restored in RAM (Main Memory) from HDD (Secondary Memory). CPU reads instructions one by one for execution.
Configuration of CPU:
Control Unit:
Control Unit issues directions to each device on the basis
of the contents of the instruction for processing. It consists of a decoder that
is used for decoding the executed instructions and gives directions.
Arithmetic and Logical Unit:
Computations relay on this Unit. ALU uses an adder for
addition, a complementary for calculating complements and such other components.
Registers:
Registers are memory devices that are used for temporarily storing data in CPU. Different types of registers are available for a different type of data.
Instruction register:
This register is used for storing instruction. it composes of two parts instruction part and an address part.
Instruction address register:
alias of this register is program counter, program register. It stores the address of the next instruction.
General register:
General registers are used as general purposes.
Accumulator:
The accumulator is used for computational purposes.
Base address register:
It stores the beginning address of a program.
Index register:
It stores the index for address modification.
Flag register:
It stores the information of certain status. Depending on the status of this register, the next action, such as the branch destination of the condition branch instruction, is decided.
PSW (Program Status Word):
It stores the running status of a program (value of program counter, value of flag register, etc).
