An Operating System is low-level software that enables a user and higher-level application software to interact with a computer’s hardware and the data and other programs stored on the computer.

His basic function is to performs basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as printers.

Application programs 

Operating systems provide a software platform on top of which other programs, called application programs, can run.

The choice of operating system, therefore, determines to a great extent the applications a user can run. For example, the DOS operating system contains commands such as COPY and RENAME for copying files and changing the names of files. The commands are accepted and executed by a part of the operating system. Similarly, the UNIX operating system has commands like CP and MV to copy and rename.

UNIX

Unix was one of the first operating systems to be written, in 1971.   Advantages of UNIX are: 

• Multitasking – multiple programs can run at one time.
• Multi-user – allows more than a single user to work at any given time. This is accomplished by sharing processing time between each user.
• Safe – prevents one program from accessing memory or storage space allocated to another program, and enables file protection, requiring users to have permission to perform certain functions, such as accessing a directory, file, or disk drive.

Types of OS

• Microsoft Windows
• Mainframe
• DOS
• OS/2
• Linux
• Mac OS
• AmigaOS

Additional service of the operatig systems is for example the Program Execution,where OS provides an environment where the user can conveniently run programs while the user does not have to worry about memory allocation or CPU scheduling.

I/O Operations consist of each program that requires input and produces output. The OS hides some of the details of the underlying hardware for such I/O. All the user sees is that the I/O has been performed, without those details.

And In the end we have Communications, where the instances where processes need to communicate with each other to exchange information. It may be between processes running on the same computer or running on different computers. The OS provides these services to application programs, making inter-process communication possible, and relieving the user of having to worry about how this accomplished.

Most popular operating systems:

• Android has the largest it is the most popular OS in Asia and Africa, by web usage. Since 2013, devices running it have been selling more than Windows,iOS,and Mac OSX devices.

https://upload.wikimedia.org/wikipedia/commons/e/ee/Android_green_figure%2C_next_to_its_original_packaging.jpg

•  Even Android the most popular smartphone operating system, on tablets iOS is still the most popular in that category.
• On the other hand,most desktop and laptop computers use Microsoft Windows, while most supercomputers use Linux.

Citations:

„Computer Basics: Understanding Operating Systems.“ GCFLearnFree.org. N.p., 2015. Web. 12 Jan. 2016.

„What’s My OS? What Is My OS?“ What’s My OS? What Is My OS? N.p., n.d. Web. 12 Jan. 2016.

Vegetarianism causes a big stir in today’s word. A person who does not include meat products of any kind in his diet is called  vegetarian.There are several levels and types of vegetarians, depending of what kind of food is excluded from their daily diets.  Because i am interested in this topic i will outline and explain the main reasons why vegetarianism is a healthy diet.

Lacto-ovo-vegetarianism is the most common type of vegetarian diet. Lacto ovo vegetarians exclude from their diets meat, but do include dairy products and eggs . While lacto vegetarians eliminate meat from their diet, they do eat dairy but exclude eggs. The most restrictive type of vegetarians are vegans ,who eliminate all animal products from their diet and don’t use any products made from animals. The last and at the same time the least restrictive form of vegetarianism is the pescatarian vegetarianism, where you avoid all meat products with the exception of fish.

By Gila Brand at en.wikipedia (Own work) [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons

Vegetarians are often known as people who are not getting all the nutrients they need in their diets,but it has been argued that from a nutritional point of view,a lot of people aren’t getting their nutrients intake right,and it is a common problem throughout the whole of the population, and there is no reason why vegetarians should be at a disadvantage (McQueen,2010).  McQueen argues that studies have actually shown that vegetarians eat 25 percent less fat and get more vitamins and nutrients compared to meat eaters. Vegetarian diets require very careful planning. Plant foods is beneficial because of the high level of dietary fibers and low level in the saturated fat than in animal foods, but the more you restrict your diet, the more difficult is to get all the nutrients you need. One commonly-held belief is that removing meat from our diet will leave us struggling to get enough protein,that’s why McQueen stresses that if you eat a balanced and healthy diet,you can still get all the nutrient you need from dairy products as for example soya,which is a complete protein as it has everything you need.

One of the most important health benefits is the reduce of blood pressure. A new scientific review shows that high blood pressure (hypertension) can be reduced with dietary changes, especially a vegetarian diet, and that vegetarian populations have lower rates of hypertension (Berkow and Barnard ,2005) and that simply adding meat to the diet increased the risk of dying from heart disease by 30 per cent. According to the American Dietetic Association, vegetarians are at lower risk for developing heart disease, colorectal, ovarian, and breast cancers,diabetes and obesity because of the low intake of fat,salts and high consume of fiber. In addition, vegetarians tend to consume higher intakes of phytochemicals, which are big prevention from cancer activity.

From my point of view it’s evident that vegetarianism ensure healthy living, but it is clear that it’s necessary to plan a vegetarian diet very carefully to make sure it includes all the essential nutrients.

Citations:

McQueen. „Changing Your Diet Is Fruitful; Becoming Vegetarian Has Many Benefits.“        Daily  Record (Glasgow, Scotland) 24 May 2010. Questia School. Web. 6 January 2016.

Berkow, Barnard. „Blood Pressure Reduced through Vegetarian Diet.“ Nutrition Health Review Winter 2005 Questia School. Web. 6 January 2016.

Sundblad, Donna. „Types of Vegetarians.“ Editorial. LoveToKnow.  Beauty & Style, Dec. 2009. Web. 6  January 2016.

By Gila Brand at en.wikipedia (Own work) [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons