what is Computer organization and architecture ? Explain

Computer organisation and architecture : computer architecture refer to those attributes of a system visible to a programmer or those attributes that have a direct impact on the logical execution of a program.

Computer organisation refers to the operational unit and there interconnections that realize the architectural specification.

Examples of architectural attributes includes the set of instruction, the number of bits used to represent various data types example numbers, characters, input output mechanism, and techniques for addressing memory.

Organisation attributes includes those hardware details transparent to the programmer. Search as control signals, interface between the computer and peripherals, and the memory technology used.

CPU organisation fundamentals : tab primary function of CPU and other instruction set processes is to execute sequence of instructions, that is programs which are stored in an external memory.
  1. Program execution is there for carried out as follows : 
  2. The CPU transfers instruction and , when necessary, their input data from main memory to registers in the CPU.
  3. CPU will process the instructions that is stored in system except when the execution sequence is explicitly changed by a branch instructions.When necessary the CPU sends output data from the CPU registers to the main memory.
If no cache memory is present as in the figure the the computer communicates directly with the main memory, which is a high capacity multi chip RAM memory the CPU is significantly faster then memory that is, it can read from or write to the CPU registers per hacks 5 to 10 times faster then it can read or write to the memory. 

There is wastage of time to handle this situation many computers have a cache memory positioned between the CPU and main memory as in figure. The cache memory is smaller and faster than the main memory and May resides, on the same chief as the CPU,it typically permits the CPU to perform a memory load or store operation in single clock cycles, whereas a memory access that bypasses the cache and it is handled by the main memory takes many clock cycles.