COA-General Computer System Model

General Computer system Model and Different Components(or units) of Computer

A Computer defined as an electronica device that operates under the control of internally stored instructions that can accept input, process data(both mathematical and logical processes),produce output and store result.

Basically, a computer transforms data into information, and to done this, there are 5 basic components/units.Means, to accomplish the above specified task, computer have 5 functional units as depicted below through the block diagram of computer.

Now, we will discuss about each in brief one by one.

   1.Input Unit:

       Input Unit contain devices with the help of which we enter data into the computer.Means with the              help of Input Unit data from outside can be supplied to the computer.

       Example of Input Devices are: Keyboard, Mouse, Hard-disk, Floppy-disk, CD-ROM, etc.,.

   2.Output Unit:

       This unit consists of devices with the help of which we can the information from computer.                        Means, with the help of Output Unit computer results can be provided to the user.

       Example of Output devices include: Printer, Monitor, Plotter, etc.,.

   3.Central Processing Unit(CPU):

       Central Processing Unit is like a brain of computer.Its purpose is to fetch binary coded                              instruction from memory, decode the fetched instructions, and then generate control signal                      required to execute the instruction and finally execute instruction.For this, Central Processing                  Unit consists three basic blocks, these are:

           Arithmetic and Logical Unit(ALU): This Unit performs Arithmetic and Logical operations                        on instructions. Arithmetic operations like - addition, subtraction etc., and Logical operations                    like Comparison, selection etc.,.

           Control Unit(CU): Control Unit generates Control signals by which it controls the operations of all             parts of computer.

           Registers: Registers are high-speed storage areas that temporary stores data during processing            i.e., they may store program instruction while it is being decoded, stored data while it is being                  processed by ALU, or store result of calculations.  

   4.Memory Unit:

       Memory Unit stores data or program either for processing or for future use. So Memory Unit, is                any hardware capable of holding information either temporarily for processing and permanently                for future use. 

       There are two kinds of Memory in Memory Unit, these are:

    

            Primary Memory: Primary Memory hold data and application temporarily. Example of                             Primary storage devices include: Magnetic Core Memory, Cache Memory, RAM, ROM, etc.,.

            Secondary Memory(Auxiliary Memory): Secondary Memory hold data and instruction for                     permanent basis.Example of Secondary Storage devices include: Hard-Disk, Floppy-Disk,                       Flash Memory, etc.,. 

   5.Bus:

       All above units are connected to each other through Buses.Means Bus is a subsystem that                      transfer data between components.A Bus is basically a set of wires that can carry data bits and                acts as a communication path between the processing unit and peripherals.