Page 21 - Computer Science Class 11 With Functions
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The read or write instructions are communicated through the control bus. Similarly, to write data into the memory,
            the CPU places the data on the data bus, and the address of the memory location where the data has to be written is
            placed on the address bus. Once this is done, a control signal is issued to write the data from the CPU to the designated
            memory location.


                     Give two examples of the following:
                     1.  The output devices that generate sound as output.
                     2.  The devices that produce a hard copy output.
                     3.  Secondary memory storage.
                     4.  Types of bus.




            1.5 Software
            Recall that a sequence of instructions given to a computer is called a program. The computer manufacturer provides
            several useful programs that help the end user to use the computer conveniently. A set of programs that performs a
            useful task is called software. Some examples of software are Microsoft Office, Adobe Photoshop, Media player, and
            Python.
            A software developer may develop a proprietary software and charge its users a one-time price or regular fee. The
            source code for proprietary software is not available to its users. Examples of proprietary software include Microsoft
            Windows  11,  Adobe  Photoshop,  and  Microsoft  Office.  However,  sometimes  a  developer  may  make  source  code
            available to its users. A software whose source code is publicly available is called open-source software. Ubuntu,
            Libre Office and Gimp are examples of open-source software (OSS). Most of the opensource software are available
            free for use, although in some cases, open source software may be chargeable. In addition, basic version of some
            proprietary software, such as Skype and Adobe Reader, is available for use free of charge, but the users who intend to
            use advanced features of Skype and Adobe must pay for their usage.
            1.5.1 Types of Software

            Depending on its use, the software is broadly categorised into two categories:
               System Software

               Application Software

                                                         Types of Software





                                        System Software                 Application Software



                                      -  Operating System              -  General or Packaged
                                      -  Device Driver                  Software
                                      -  Language Processor            -  Customized Software
                                      -  Utility Software


                                                      Fig 1.8: Types of Software







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