Compare And Contrast Os Computer Science Essay

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In operation system is a software program it enables the computer hardware communicate and operate the computer. The operating system is comprised of system software, or the fundamental files your computer needs to boot up and function. The common mobile phone operating system includes windows mobile, and Linux. In most areas, the survey is extremely brief because it is assumed that the reader is familiar with the subject. However, several areas are covered in some detail because of their importance to topic covered in the book. The types of operating system have progressed and developed so have the operating systems.

Basic list of the operating system and a few example of operating system that falls into each of the categories. Once the input has been processed, it is output to a monitor, printer, and disk or sent via email or the web. There are a few basic tasks that performed by operating systems such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directory on the disk, and also controlling marginal devise such as printers, scanners machines, and also fax machines. Many computer operating systems will fall into more than one of the below categories. An operating system manages all the input getting information into the computer from an external source as the keyboard, a mouse, a scanner, or a disk. The processing, after receiving input, the computer manipulates or alters the data.


An efficient operating system always aim high throughput which measures the amount of work a processor can complete within a certain time period and also always minimize the time taken or spent in providing any services. The below basic list a different operating system and also a few example of operating system that fall into each of the categories. In many computers operating system will fall in more than one below categories. It is window 98, GUI, UNIX, Linux and so one.

Answer of question 1

In operating system we can see so many available in market today. The multi user operating system allows for multiple users to use the same computer at the same time and different time. Below is some example of operating system. The most famous in market is UNIX, Linux, window XP, window vista, window 7 and window 8.

The first that available in market today is UNIX. Since the operating system 1980’s UNIX main competitor windows has gained popularity due to the increasing the power. The UNIX was developed at Bell Labs in 1969. In UNIX is a powerful and multi user environment that has been implemented on a variety of platforms. The exception of Microsoft Windows, all current major operating systems have some kind of UNIX at their cores. They are so many different type of graphical interfaces, but from the UNIX shell, a command line feature common all version, they are very similar.

The advantage of UNIX is more flexible and can be installed on many different types of machines, including main frame computers, supercomputer and micro computer. When we use the UNIX that is more stable and does not go down as often as windows does, there requires less administration and the maintenance. The UNIX use a greater built in security and permissions features than windows. In UNIX is the leader in serving the web. About 90% of the internet relies on UNIX operating systems running the world most widely used web server. It from Microsoft requires the user to purchase new or more hardware or software. That is not the case with UNIX. Linux is, in simplest terms, an operating system. The operating system relays instructions from an application to, for instance the computer processor. In this system there is a rich set of small commands and utilities that do specific tasks well and it do not jumbled up with lots of special options. UNIX/Linux is a very well-stocked toolbox. The processor performs the instructed task, then sends the results back to the application via the operating system. Windows and OS are predominantly found on computing devices such as desktop and laptop computers.


The second is Macintosh it called the Mac. It does introduce in 1984 by apple computer. Macintosh was designed to provide users with a natural, intuitively understandable, and in general user. This includes the mouse, the use of icons or small visual images to represent objects or actions. The Macintosh has its own operating system, Mac operating system which, in its latest version is called Mac operating system. The microprocessor, Mac versions today are powered by the power PC microprocessor, which was developed jointly by apple, Motorola, and IBM. The Mac App Store allows the users to discover, purchase and even download application directly on their Mac easily.

The next is window. In window have so many type of windows. They are window8, window7 and window XP. Bill Gates announced Microsoft Windows in the early of 1983’s. Every version of Window’s which includes a graphical user interface; with a desktop always allow the users or any programmers to view files and folders in windows. Window 8 is a totally new version of windows that, in addition to the desktop, also includes a new style interface for use with touch screen. Window 8 is an operating system produced by Microsoft for use on personal computer, including home and business desktops, and home theater PCs. Windows 7 was a big hit for Microsoft, turning things around from the troublesome Windows Vista and reminding people that the Redmond giant was not quite ready to hang up its hat just yet.

For window vista home and business desktops and portable computers. Similar to window XP starter edition, this edition was limited to emerging markets. Windows vista center edition, this addition did support more advanced multimedia and entertainment authoring. Window XP is an operating system produced by Microsoft for use personal computers. Window XP, the successor to windows 2000 was the first consumer oriented operating system produced by Microsoft. Window XP comes in two versions, home and professional. The company has focused on mobility for both editions, including plug and play version.

Conclusion of question 1

In the conclusion, UNIX /Linux and windows are very important for operating system. And also very useful for the system. Without a computer operating system, a computer would not use. However, all the fundamental applications are available, and the Macintosh is a perfectly useful machine for almost everybody. The UNIX you have in general the option of using either command lines or GUIs. For many others are not aware that there are operating systems other than windows. But you are here reading about operating systems, which probably means that you are trying to make conscious OS decisions for home use or for your organization.

Introduction of Question 2

If your computer is lacks the random access memory (RAM) needed to run a program or operation, windows uses virtual memory to compensate. Virtual memory combines your computers RAM with temporary space on your hard disk. One or more than one RAM chips which each of them do have memory modules. The amount of real memory in a computer is limited to the number of RAM is installed. Virtual memory combines your computer RAM with temporary space on your hard disk.

When the RAM run very slowly, virtual memory moves data from ram to a space it’s called a paging files. It stores the most recently items in RAM and later store the less used items in the slower disk memory and interchanging data between the two whenever a disk access is made.

The moving data to and from the paging file frees up RAM to complete its work. The RAM in your computer has the faster you programs will run. However, your computer can read data from RAM much more quickly that from a hard disk. The most items in RAM and later store the less used items in slower disk memory. For the virtual memory capable to write a program without knowing the physical layout of memory. For example, virtual memory might contain twice as many addresses as main memory.

Answer of Question 2(a)

The virtual memory is hardware that your computer uses to load the operating system and also run the programs. The RAM chips that each has several memory modules. The amount of real memory in a computer is limited to the amount of RAM installed. In paging computer operating system that have their main memory divided into pages, paging is a transfer of pages between main memories, such as a hard disk drive. The process may also run if the page is currently referencing is in the main memory. When the systems transfer any page from the secondary storage to main memory, hence it will locate the page in the main memory block which is called page frames. Paging is an important part of virtual memory implementation in most general purpose operating system, allowing them to use disk storage for data that does not fit into physical RAM. In modern server operating system we can use multiple size support. That actually helps to tune OS performance, depending on type of application.

In secondary storage, is memory external to the main body of the computer CPU where programs and data can be stored for use. These devices must be connected to a computers external I/O ports in order to be accessed by the system. They may or may not require own power supply. Moreover, each table has an entry for address which is called as Page Table Entry (PTE). There are two types of page tables such as multi level and also inverted. Multilevel allows the address to be arranged in the hierarchy types of table while inverted allow to store the address into exactly one PTE for each page frame as a whole page.

Direct mapping is a method of storing information for easy access on a computer. in operating system, a cache is a small section of random access memory that is aside for the purpose of easily retrieving data. The mapping can increase one way only that is the dynamic address translation is to place the entire page. It is very expensive than direct mapped cache memory. The direct associative mapping which is the combination of both mapping of direct and associative. It allows the processes of these values to be execute urgently.

The segmentation is one of the approaches to memory management and protection in the operating system. It has been superseded by paging for the most purposes, but much of the terminology of segmentation. The size of an entire set of similar items, such as a set of instructions in a producer or the contents of an array, which allows the systems to protect items. Some operating systems still have segmentation is at some logical level although paging is used as the main memory management. The segmentation is actually a way to keep similar objects in one place. For example is, you can have your stack stuffs in the one place, the binary code in another place, and the data is in another place. If the currently running process is allowed by the permissions to make the type of reference to the memory. The flag of indicating whether the segment is present in main memory or not and if the segment is not present in main memory, an exception is raised, and also the operating system will read the segment into memory from secondary storage. The information indicating where the segment is located in memory might be the address of the first location in the segment.

Answer of Question 2(b)

The interrupt is a dynamic event that needs prompt attention by the CPU. Always the interrupt only needs a short period of CPU time to serve it. After that only the original process can resume its execution. The attention of the CPU, it can interrupt the execution of the current process holding the CPU and it can save its key state information in memory or hard disk.

The next is interrupting processing. The process is a program in execution. Its state includes the executable code and data in the main memory, the value of the program counter and the values of all the general purpose registers. After the interrupt line had becomes active, the processor completes implementation of the current instruction, then pauses the implementation of the current process. The process is higher priority needs to get prompt attention from the CPU; it can be the interrupt execution of the current process holding the CPU. Interrupt processing is at the core of modern operating system implementation. These interrupts occur when the channel subsystem signals a change of status, such as an input and output operating completing, an error occurring. The external interrupt can indicate any of several events, such as a time interval expiring, the operator pressing the interrupt key on the console.

These interrupt are caused by program errors, page fault or the requests to monitor an event. When the interrupt occurs, the hardware saves pertinent information about the program that was interrupted. The interrupt vector is located in memory that processes cannot access. The hardware then routes control to the appropriate interrupt handler routine. The program status word or PSW is a key resource in this process. Which is the processing doing a lot of other core of operating system functions in all but the most modern operating system.

Conclusion of Question 2

The conclusion of question 2 is the virtual memory management functions windows offer direct management of virtual memory in Windows NT. Within each region are one or more pages of addresses that also carry protection. The virtual memory management functions provide capabilities for applications to alert the state of the pages in the virtual address space. The virtual memory functions are considered low level functions, meaning they are relatively fast but them many high level features.