Programming Languages

Programming Languages

By rsktutors   Tuesday, October 04, 2016   No comments:

Programming Languages

        A program is one of the most popular words, we use in our regular life. In general, the program means an occasion. That means we are doing some event, because of some purpose. Similarly, in computers also, we are going to do tasks with the help of programs. Actually, before writing this article, my daughter asked me a bunch of questions. Those questions make me motivate to collect and share the following information about programming languages. Let us start our discussion about programming languages with meaning.

        For doing things with computers, we must provide commands to the computer in the form of statements. All these statements are known as Instructions. That means, before assigning all these instructions to the computer, we must group these instructions together as a block.

        This group of instructions to complete a task successfully is known as a Program. Of course, some programs are not executed successfully, means that the result of those programs,  may not help for users. Even though there is no use with that type of statements, we call them as programs. In my point of view, those are known as Virus Programs.

        Whatever may be, a successful or unsuccessful group of instruction given to a computer to perform a certain task is known as a Program. That means to assign work to the computer, we must provide with a group of instructions/commands/statements. To do this, we use a language known as Programming Language. There are so many programming languages are available. A programmer(who writes the program) his choose his convenient language to write the program. Usually, we write instructions in normal public using language like English. So, these languages are known as High-Level languages.  Once, we wrote a program using any high-level language, that has to be translated to machine understandable language(Low-Level Language). This responsibility has been taken by either compiler or interpreter. So, technically saying, a Programming language is a special language used by programmers to develop applications. The first programming language was developed by Konrad Zuse is Plankalkul in between 1943 and 1945. But it actually came in practice in 1998.

        Now I would like to introduce few important(according to me) programming languages. Let's begin our tour.

1957-1960:

FORTRAN

FORTRAN stands for FORmula TRANslator/TRANslation. It was the first and oldest computer programming language developed at IBM by John Backus. The first version was released in the year 1957 for the computer model IBM 704.  In 1958, IBM released FORTRAN II( Second version of FORTRAN) with functions and subroutines. In 1966, ANSI (American National Standard  Institute) released FORTRAN 66. It was the first Formal Standard Programming language. In 1977, X3J3(ANSI FORTRAN Standards Committee) added true block IF statement, direct access I/O, Character Data type, Parameter Statement for defining Constants and released with name FORTRAN 77. This version becomes most popular used programming version. In 1991, ISO(International Standard Organization) released FORTRAN 90.  

LISP

LISP stands for LISt Processor. It was developed by John McCarthy in 1960. Based on the idea: Computing is done with symbols rather than numbers, LISP was designed. Usually, it is used in Artificial Intelligence research Program.

  

COBOL

COBOL stands for Common Business Oriented Language. It was developed in 1959 by CODASYL(Conference on Data Systems Languages). It is the second oldest high-level programming language. It was developed by Grace Hopper and Bob Bemer. In 1968, ANSI(American National Standards Institute) developed a standard form of language known as ANS COBOL. Again in 1974, ANSI released revised version. By adding new features, in 1985 ANSI published another version. COBOL 97 version has both conventional and object-oriented features. COBOL is very good for solving business problems. 

1970:

PASCAL

PASCAL is a high-level programming language. It is also known as general purpose programming language. It was developed by Niklaus Wirth in the year 1970. Pascal is based on Algol(Algorithmic Language). PASCAL is not an acronym. It was named with 17th-century mathematician Blaise Pascal. It is strongly typed language. It comes with several data types like records, sets, files and arrays. It supports with functions and procedures.

1972:

C-Programming Language

C Programming language was designed at Bell Laboratories in 1972 by Dennis Ritchie. It is the branch of BCPL(Basic Combined Programming Language). In 1978, The C programming language was published by Kernighan and Ritchie. In 1983, ANSI started a project for a standard version of C. In 1988, ANSI released standard version known as  ANSI C. C-programming language has so many features like Reliability, Flexibility, Modularity, Portability, Interactivity, Efficiency, and Effectiveness. UNIX operating system was developed by using this C-Language. This language is used to develop verity of system applications like Graphics Package, Database Systems, Spreadsheets, Word processors, Operating Systems, Compilers, Assemblers, Interpreters and Network Drivers.

1983:

C++

The title C++ is originated with "C with Classes". C++ is a high-level programming language. It was developed by Bjarne Stroustrup in the year 1979. The first C with Classes was called Cfront. it was derived from C-compiler Cpre. In 1983, the name C with Classes changed to C++. In 1985, C++ programming language was released. In 1990, Annotated C++ reference manual has been released. In 1998, first International Standard for C++ ISO/IEC 14882:1998. Informally this is known as C++98. C++ includes with object-oriented features such as classes, inheritance, abstraction, encapsulation and polymorphism.  C++ continues to be updated. In 2011, current version C++11 has released.

1987:

PERL

PERL is the short form of Practical Extraction and Reporting Language. It is an Open Source Programming Language, designed by Larry Wall in the year 1987. This language is very similar to C-Programming language. In 1988, PERL II with regular expression engine feature was released. By adding support for binary data streams, in 1989, PERL III was released. In 1993 and 1994, PERL IV and PERL V were released successively. On 13 March 1995, PERL 5.001 was released. On July 22, 1998, PERL 5.005 was released. On March 22, 2000, PERL 5.6 was released with 64-bit support.  The latest version PERL 5.13.9 released on 21 January 2011 by Jesse Vincent. It is the most commonly used language for CGI(Common Gateway Interface) scripts.

1991:

PYTHON

Python was developed by Guido Van Rossum in the year 1991. It is an Interactive, Interpreted, Object-Oriented Programming language. The first implementation standard was released in the year of 1989. Version 0.9.0 was released on 20 February 1991.  Later , in this month itself, version 0.9.1 was released. During last months of 1991, version 0.9.2 was released. On 24 December 1991 version 0.9.4 was released. After continued updated versions, the latest version Python 3.0 was released on 3 December 2008. In the version 3.0, print  function made as a built-in function and changed integer built-in functionality. Ex: in Python 2, result for 7/2=3. But in Python 3 the result is 3.5. Its main syntax and some aspects are taken from the basic language ABC. At the same time some syntax provided by the C-Programming Language. Regular expressions for string manipulations are based on PERL. In some cases, additions and some syntactical choices were strongly influenced by the JAVA language.

1993:

RUBY

RUBY is a high-level programming language. It is also known as general purpose programming language. It is an open-source, object-oriented programming language. It is mainly focused on simplicity and productivity. A framework knows as Ruby on Rails is using developing web programming. The first version Ruby 0.95 was released in the year 1995, Later the version RUBY 1.9.3 was released in the year 2011. It was designed and developed by Yukihiro Matz Matsumoto in Japan in the year 1990. RUBY was influenced by Smalltalk, Perl, Eiffel, Lisp and Ada. It has a dynamic type of system and automatic memory management. It is having four levels of variable scopes which include, Class, Local, Global and Instance. It supports Exception Handling, Operator Overloading, Garbage Collection and default arguments. It is having  centralized package management through RubyGems. It is also implemented on all major platforms. It is having a large library modules for HTTP(Hyper Text Transfor Protocol), FTP(File Transfer Protocol), YAML(Yet Another Markup Language), XML(Extensible Markup Language), JSON(JavaScript Object Notation), OpenSSL(Open Secure Sockets Layer), RSS(Really Simple Syndication), Tk, Curses, and Zlib(Zip Library). The syntax of Ruby is most similar to Python and Perl.   

1995:

JAVA

JAVA Programming language was developed by James Gosling at Sun Micro Systems in the year 1995. The original name for JAVA is Oak. This language is popularly used for developing Internet Applications. With the Help of this JAVA programming Language, We can develop Web applications as well as Network Programming and Standard alone applications. Today JAVA is owned by Oracle.

In beginning days, Java starts with a group of team members known as Green Team. In the year June 1991 James Gosling, Patrick Naughton and Mike Sheridan were initiated Java language project. In the beginning days, it was designed for small and embedded systems in electronic devices like set-up boxes. It was Greentalk  and has the extension .gt .Later as a part of Green project, it was named as Oak. In the year 1995, Oak was renamed with JAVA. Because Oak is already used as the trademark for Oak Technologies. There were several versions of Java has been released. They are, In 1995, JDK Alpha and Beta version, On 23 January, 1996 JDK1.0, On 19 February, 1997 JDK1.1, On 8 December, 1998 J2SE1.2, On 8 May, 2000 J2SE1.3, On 6 February 2002 J2SE1.4, On 30 September 2004 J2SE5.0, On 11 December 2006 JAVA SE6, On 28 July 2011 JAVA SE11, On 18 March 2014 JAVA SE8 were released.

JAVA includes features like Simple, Object-Oriented, Platform Independent, Robust, Secured, Architecture neutral, Dynamic, Portable, Interpreted, High Performance, Multi-threaded and Distributed.    

PHP

PHP Stands for Hypertext Pre Processor. It was developed by Rasmus Lerdorf in the year 1994. On June 8, 1995, PHP has been publicly released. The main purpose of PHP is to develop Dynamic Web Pages deals with databases. It is a Server side Interpreted scripting Language. PHP takes most of its syntaxes from C-Programming Language. PHP runs on Web Server. PHP developers can be classified as Web Developers or Software Developers. PHP code may be included into HTML code  or it can be used in combination of different web templates, web content management, web frameworks.

JAVASCRIPT

 JavaScript was developed by Brendan Eich, which was initially known as LiveScript. In the year May,1995 LiveScript was renamed with JavaScript.  It is an Client-Side scripting Language. That means it executed on Client machine web browsers. JavaScript allows us to insert into our web page. JavaScript mostly placed in HTML(Hyper Text Markup Language) or ASP(Active Server Pages) files.

JavaScript comes with features like, Variables, Objects, Arrays, Operators, Methods, Functions, Conditional Statements ,Loops, Event Handlers and Comments.

With all this information, I hope you will get a brief introduction and information about various programming languages and their unique features. See you in my next article. Finally, Please feel free to give comments and suggestions in the below section.

Thank You.  

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WINDOWS OPERATING SYSTEMS

WINDOWS OPERATING SYSTEMS

By rsktutors   Tuesday, October 04, 2016   No comments:

 MICROSOFT WINDOWS OPERATING SYSTEMS

Dear reader,

In my previous articles, we discussed the history of computers, software history and evolution of hardware concepts. Now, I would like to share my views on Operating System. Mainly I am focusing in this article about the meaning of Operating system and evolution of Windows Operating systems.

Let's begin with meaning and purpose of an Operating system.

Operating System(shortly OS) is the most important software in any computer system. As I discussed in my previous article software history, software can be classified into two categories. They are System Software and Application Software. Operating System comes under System Software category. Operating System is a specialized software, designed for utilizing our computer system properly.

Almost every computer has its own operating system. This operating system takes the responsibility to handle all other programs, applications, and even other hardware components. In performing every task in a computer system, operating system plays a vital role. By simply saying, without an operating system, our computer is useless. An operating system performs I/O management, Memory management, Multi-tasking, Peripheral management, Security management and everything. That means an operating system acts as a mediator between the computer and the user. Operating Systems can be mainly classified into the following types.

Multi-User Operating System:

          This type of operating systems permits two or more users to do operations at the same time. Now a day's an operating system allows hundreds of users to work concurrently(performing different tasks at the same time). Ex: Windows NT, UNIX.

Multi-Processing Operating System:

        Multiprocessing operating system allows, use of more than one CPU (Central Processing Units) in a single computer system. These CPUs share common computer peripherals like memory, bus and other. These systems are also known as Tightly Coupled Systems.

Multi-Tasking Operating Systems:

        Multitasking operating systems allow, run more than one program at a time. That means multiple programs are running concurrently. To do this, Operating systems follows Scheduling concepts.

Multi-Threading Operating Systems:

          Multithreading means dividing/splitting a single program into more small tasks and execute them concurrently.

Real-Time Operating Systems:

          These operating systems respond to given input instantly. Ex: General purpose operating systems like DOS and UNIX.

        As we discussed in the beginning of this article, we must take help from operating system to do any task. For this, we have to interact with the operating system. This interaction can be done with commands. Ex: in DOS for copying files we use COPY command. These commands are the takeover of the operating system and executed by the processor. Suppose, if you are using Graphical User Interface, you can do this by clicking the objects that are visible on the screen.

      

  Now it is the time to take a journey of Microsoft's Windows operating Systems. Windows operating systems owned by Microsoft. This journey starts to form the year 1985. Microsoft windows is a user-friendly operating system, mainly target to personal computers.

Microsoft Disk Operating Systems(MS-DOS):

        DOS was originally developed by Microsoft for IBM compatible personal computers. Initially, DOS is very similar to CP/M(Central Program for Microcomputers). Later it was adopted to minicomputers. DOS is purely command based oriented operating system.

Windows 1.0:

          Windows 1.0 was introduced by Microsoft in the year 1985. The window was named because of computing boxes. Unlike DOS, Windows 1.0 allowed users, they can point an object and choose the particular object by click with a mouse(input device).

Windows 2.0:

    

      Windows 2.0 was released by Microsoft in the year 1987. This OS(operating System) was designed for Intel 286 processor. It includes keyboard shortcuts and icons.

Windows 3.0:

        Windows 3.0 was released by Microsoft in the year 1990, by introducing better icons , graphics with 16 color for Intel 386 processor. This version supports File management, Program management, Print management, games like Minesweeper, Solitaire and Hears.

Windows 3.1:

        Windows 3.1 was released by Microsoft in the year 1992. In this version, icons come with can drag and drop feature. It was the first version of windows distributed with CD-ROM. This version also introduced Window Registry, Centralized Database, History Management.

Windows 95:

          Windows 95 was released by Microsoft in the year 1995. It supports 32-bit applications. This version improved with windows control and appearance control, Desktop design, right button menu, help system, task bar, start menu and built-in network support with dial-up for different protocols. This is the first Windows operating system which allows file with long names. It also supports with Plug-and-Play feature with hardware components.

Windows 98:

        Windows 98 was released by Microsoft in the year 1998. It comes with a lot of new technologies like FAT32(File Allocation Table, data stored in chunk of 32 bits),  AGP(Accelerated Graphics Port), MMX(Multi Media eXtensions), DVD(Digital Versatile Disk), USB(Universal Serial Bus), ACPI(Advanced Configuration and Power Interface).

Windows ME:

      

     Windows ME(Millennium Edition) was released by Microsoft in year 2000. Actually, it was an update of Windows 98. This version includes a lot of new features, and removed the option boot in DOS. In this version Microsoft added the Image acquisition feature to download images from digital cameras. New tool Movie maker was included to edit movie files as per user requirement. Windows ME also supports new home networking wizard to collaborate with different computer peripherals and other computers with in a home or an office.

Windows NT 3.1 - 4.0:

          Windows NT(New Technology) versions 3.1 to 4.0 were released in the mid years 1993 to 1996. It is an 32-bit operating system which supports preemptive(by interrupting running task for some time and then resumed after some time when the more priority task has finished its execution)  multitasking. This version is mainly focused on Client-Server technology.

Windows 2000:

  

      Windows 2000 was popularly known as W2K. This development was dedicated for business desktops and laptops which are connected through a network and execute software applications, sharing files, printers and other network resources. Microsoft has released 4 versions under this category. They are namely, Windows 2000 Professional meant for business desktops, Windows 2000 Server meant for both web server and Office server, Windows 2000 Advanced Server meant for Line-of-Business Applications and Windows 2000 Datacenter Server meant for High-Traffic Computer Networks.

Windows Xp:

       

   Windows Xp(Experience) was released in the year 2001. Windows Xp was released in 2 versions. They are namely, Windows Xp Home Edition and Windows Xp Professional. Windows Xp was one of the most popular operating system in Microsoft Operating system family. This Windows Xp operating system utilizes 802.11x wireless security standard.

Windows Vista:

     

   Windows Vista operating system was released in the year 2006. This version has the capabilities to detect the several hardware problems. This version uses least power consumption. It comes with a very good enhancements in reliability, ease of deployment, manageability, security, performance over the previous version Windows Xp.

Windows 7:

          Windows 7 was released in the year 2009, October 22. It allows multi-touch support, IE8(Internet Explorer), virtual had disks, improved media player and great security features.

  

Windows 8:

    

      Windows 8 was released in the  year 2012, This version was developed on touch screen feature. This operating system load within seconds. It uses metro design system interface which used in windows Phone 7 mobile operating system.  This Windows 8 operating system supports x86 Personal computers and ARM(Advanced RISK Machine) processors.  

  

Windows 10:

     

   Windows 10 was released in the year 2015. This version has Microsoft Edge(replacing to Internet Explorer) and Microsoft' new browser, Central Notification Center, Universal Apps.

With this whole journey, I hope you should understand the various versions and their features of Microsoft Windows Operating System.

See you with my next interesting article. Please feel free to give any comments and suggestions in the below section.

Thank You.

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Hardware

Hardware

By rsktutors   Tuesday, October 04, 2016   No comments:

Hardware

Welcome dear reader,

In my previous article (Software), I have shared  my views about software history and various types of software up to certain extent. Now in this article, I would like to expose my little knowledge about hardware. To write this article I made, a tiny research regarding this topic in various books and several websites. I would thankful to all who tried to  provide, a valuable information to the world. Let's begin with a basic question, What is Hardware?

What is Hardware?

        In simple words, those devices which are having touchable property are simply known as Hardware components. Another simple word is Hardware is a physical component, whereas Software is a logical component. In general, all physical components come under Hardware. For example, see around you. Your table, your chair, your door, your pen, your book your fan, your light, your speakers, your monitor, your keyboard, your mouse, and so on. 

Good, once again observe the above examples. Monitor, keyboard, mouse, printer, scanner, CPU belongs to your computer. What are these known as?  Yes. You are right. These are the perfect examples of Hardware devices for a Computer System.

Let us move to next step. Suppose we are having excellent Operating System (Software) but, we don’t have these hardware components. What is use? nothing. Because, to utilize and get the benefits of software, we must need Hardware components. To fulfill our needs, we must have both hardware and software together in one machine. This machine is known as a perfect computer system. We can classified hardware components into mainly two categories, namely External Hardware and Internal Hardware. Now let us discuss some of the external hardware.

Floppy Disk Drive (FDD):

Up to the year 2000, these floppy drives plays a vital role in storing information. Let us see some history if these FDDs. These Floppy disks are available in different sizes with different storage capacities. In 1971, the first disk drive was made with the size 8 inch. But the drives with size 5 1/4-inch floppy disks were used practically. Then, these are replaced with 3 1/4-inch floppy disks. The 5 1/4-inch disk has the storage capability up to 1.2MB, the 3 1/4-inch disk has the storage capacity 1.44MB. But today, these are not using due to their limited capacity. These were replaced with CD-ROM, DVD-ROM, and Flash Drives.

CD-ROM (Compact Disc-Read Only Memory):

CD-ROM is an optical storage device, which holds data. This data may be either software, audio or even video. The general storage capacity of a CD-ROM is 700MB. There are different types of interfaces that allow a CD-ROM like, IDE/ATA(Integrated Device Electronics/Advanced Technology Attachment), Panasonic, Parallel, PCMCIA(Personal Computer Memory Card International Association), SATA(Serial Advanced Technology Attachment), SCSI(Small Computer System Interface), USB(Universal Serial Bus). 

The following table helps you to understand the different speeds of CD-ROM

Drive Speed	Transfer Rate (Mbits/Sec)	Access Time (ms)
1x	1.2288	400
2x	2.4576	300
4x	4.9152	150
6x	7.0653	150
8x	9.8304	100
10x	12.288	100
18x	21.8343	90
20x	Up to 24.576	90
32x	Up to 39.3216	85
36x	Up to 44.2368	80
52x	Up to 63.8976	80
72x	Up to 88.4736	75

Digital Versatile Disc(DVD):

A DVD helps us to store a large amount of data starting from 4.7GB onwards. In 1997, first DVDs were sold. To read the data from a DVD, you must have a DVD drive and its corresponding software installed on your computer. The following table describes the storage capacities of different types DVDs.

DVD Type	Storage Capacity
Single sided-single layer	4.7GB
Single sided-Double layer	8.5 to 8.7GB
Double sided-Single layer	9.4GB
Double sided-Double layer	17.08GB

 Now let us discuss the brief history of DVD. In 1993, two video disc formats have been developed. Namely, MMCD(Multimedia Compact Disc), SD(Super Density) disc. Later, Philips, Sony, Hitachi, Pioneer, Toshiba have combined the two formats and developed single DVD format. On 25, March 1996, the first feature film put on DVD was Twister.

BD(Blu-Ray):

This BD also comes under optical storage disc, which was developed by 13 consumer electronics and PC companies includes DELL, HITACHI, HEWLETT, PACKARD, LG, PANASONIC, SONY, MITSUBISHI, and TDK.  On 4 January, 2006 first Blu-Ray disc was introduced at CES(Consumer Electronics Show). It can store up to 25GB(in Single layer format) and 50GB(in Dual layer format).Today BDs are available with 200GB storage capacity.

 HDD(Hard Drive Disc):

It is non- volatile(Retaining data even if a break in the power supply) memory hardware device, having permanent storage capacity and retrieving feature. In general 3.5inch HDDs are for desktops and 2.5inch HDDs for laptops are available. HDD holds one or more platters (it is one or more Aluminum, Glass or Ceramic Disk that is coated in a magnetic media and situated in hard drive for the sake of storing information permanently). This HDD is going to connect to the motherboard with the help of any one of ATA, SATA or SCSI cable. With the help of Power Supply Unit (PSU), it will get the power supply. These HDD are using to store any type of data includes, text, graphics, images, audio and video files.

Now see some history of HDD. On 13 September 1956 IBM introduced and Marketed. The first HDD used in RAMAC 305(Random Memory Access Accounting) with the storage capacity of 5MB at the cost about Rs.33,53,740/-. 2.6MB HDD was developed by IBM on 1963. In 1983, 3.5inch HDD was developed and introduced by Rodime with a storage capacity of 10MB. In 1992, In 1992, Seagate introduced 7200 RPM(Revolutions per Minute), in 1996, 10000 RPM HDD , in 2000, 15000 RPM HDD was released.

FAN:

FAN is a hardware device which helps to cool the overall computer. There are various types of fans are used in a computer system. Namely, Case Fan, CPU Fan, Power supply Fan and Video Card Fan.

HEAT SINK:

 It is an electronic device that a part of FAN. There are mainly two types of heat sink, Namely, Active heat sink(uses power and fan type) and Passive heat sink(made up with Aluminum finned radiator

  

Motherboard:

It is also known as Main board or mobo or baseboard or planar board or system board or logic board. It is a printed circuit board located in CPU cabinet. There are several components are available on a motherboard. They are namely, Expansion slots, 3-pin case fan connectors, back pane connectors, heat sink, 4-pin power connector, inductor, capacitor, CPU socket, Northbridge, Screw hole, Memory slot, Super I/O, ATA disk drive primary connection, 24-pin ATX power supply connector, serial ATA connections, Coin cell battery, RAID, System panel connectors, FWH, Southbridge, Serial port connector, USB port connector, Jumpers, Integrated circuit, 1394 headers, SPDIF ,CD-IN, BIOS, Bus, Cache memory, Chipset, Diode, Dip switches, Fuse, Game port, Internal speakers, Keyboard controller, LCC, SIMM, Parallel port header, PS/2 header, Resistor, RTC, SCSI, Voltage regulator, Voltage regulator module  and some other.

RAM(Random Access Memory):

Random Access Memory is also known as Main memory, System Memory or Primary memory. It is used to store the information into the computer or to retrieve the information from the computer.RAM is usually related with DRAM. It retrieves the data randomly instead of Sequentially. There are several types of RAMs like, DIMM(Dual inline Memory Module), RIMM(Rambus Inline Memory Module), SIMM(Single Inline Memory Module), SO-DIMM(Small Outline Dual Inline Memory Module).

External Hardware Components:

FPD(Flat Panel Display):

It is a thin screen display module. Today we see this FPD in almost all portable computers. It is a new standard for desktop computer systems. It uses Liquid crystal display(LCD) or Light Emitting Diode(LED).

Monitor:

The monitor also is known as Video Display Unit(VDU). The monitor is used as output device. The result which was processed by the computer processor will be seen through the monitor.

Keyboard:

The keyboard is a primary input device. Because in most of the cases, we supply input data to the computer for processing. Today keyboard model is based on the typewriter. This typing device was developed by Christopher Sholes in 1868. With the help of this keyboard, we can input alphabets, digits, special characters as commands to the computer.

Mouse:

The mouse is an external hardware device, usually help in locating (x, y) position on the display system. Hence, it is also referred as X-Y position Indicator. Today mouse has mainly 3 buttons. Namely, Left Button, Right Button and Middle Button(Scroll wheel).

With all this, I hope, you understand different hardware components. Of course, there are some other hardware components like printer, scanner, speakers, Plotter, Flash drives are also available.

Please feel free to give comments or suggestions under below section. See you in my next article.

Thank you.   

.

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