Page 8 - DCAP105_WORKSHOP_ON_COMPUTER_HARDWARE_AND_NETWORK
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Workshop on Computer Hardware and Network




                    Notes          be clearly understood. For convenience, the hardware of a computer can be classified in the
                                   following categories:
                                   1.  Input Devices

                                   2.  Output Devices
                                   3.  Central Processing Unit (CPU)
                                   4.  Memory or Storage
                                   5.  Motherboard

                                   Let us discuss each of these hardware components:
                                   1.  Input Devices: The form in which data is available to a user is not always in the same form
                                       as is accepted by computer hardware. Input devices are hardware equipment that receive
                                       data and instructions from users, convert the data and instructions into a form that can be
                                       processed by the computer and passes the same to the computer. Hence, if you have to
                                       enter employees’ names into the computer you do not have to write it on a piece of paper
                                       and shove the paper inside the computer. You will need some input device for this.


                                          Example: A keyboard is an example of input device.
                                   2.  Output Devices: The result, produced by a computer after processing, is not always in user
                                       readable form. An output device is hardware equipment that translates this non-readable
                                       result into a form understood by the users.


                                          Example: A VDU (Visual Display Unit) or monitor is an example of output device.

                                   3.  Central Processing Unit (CPU): Central processing unit is to computer what brain is to our
                                       body. It is the master organ of a computer. No computer can exist without a CPU. It is
                                       composed of two simpler hardware units - Arithmetic Logic Unit (ALU) and Control Unit
                                       (CU). CU controls all the activities of other hardware units while ALU performs all the
                                       calculations. Computer CPUs are very fast in their calculations and swift in control.
                                   4.  Memory or Storage: This hardware is the place where a computer stores all the data and
                                       instructions given to it. The results of the processing are also stored here. A computer has
                                       many types of memories. Some  memories are directly connected to the CPU and are
                                       extremely fast as far as storage and retrieval of data is concerned. These memories are
                                       called  primary  memory  - RAM  (Random  Access  Memories) and  ROM (Read  Only
                                       Memories) belong to this  category of  memories. The CPU takes data and  instructions
                                       stored only in the primary memories.




                                     Notes  Primary memories are also of various types. The one that looses its contents when
                                     power is switched off is known as volatile memory such as RAM. Some memories retain
                                     the data and instructions stored on them even after the power is switched off such as ROM.
                                     These memories are known as non-volatile memories.

                                     Secondary storage devices are placed outside the system unit and can be carried from one
                                     system to another allowing portability of data and instructions. Floppy disks or diskettes,
                                     hard disks and CD-ROM are some of the secondary storage devices. Input devices, output
                                     devices and secondary storage devices are not directly connected to the CPU and hence are
                                     known as peripheral devices or simply peripherals.




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