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RICHFIELD GRADUATE INSTITUTE OF TECHNOLOGY (PTY) LTD
FACULTY OF INFORMATION TECHNOLOGY
OPERATING SYSTEMS 600
2ND SEMESTER ASSIGNMENT
Name & Surname: ICAS No: Qualification: BSC IT Semester: 2 Module Name: OPERATING SYSTEMS 622 Date Submitted: 18/4/ ASSESSMENT CRITERIA MARKS ALLOCATION
EXAMINER
MARKS
MODERATED
MARKS
MARKS FOR CONTENTS
QUESTION 1 50
QUESTION 2 40
TOTAL MARKS 90
MARKS FOR TECHNICAL ASPECTS
1. TABLE OF CONTENTS
Accurate numbering according to the numbering in text and page numbers.
2. LAYOUT AND SPELLING
Font – Calibri 12 Line spacing - 1. Margin should be justified.
3. REFERENCE
According to the Harvard Method
TOTAL MARKS 10
TOTAL MARKS FOR THE ASSIGMENT 100
Examiner’s Comments: Moderator’s Comments: Signature of Examiner: Signature of Moderator:
TABLE OF CONTENT
Question 1: Four different definitions and explanations of operating system. Question 2: A. Critically explain two problems in multiprogramming and time-sharing environment. B. Can we guarantee the same degree of security in a time-shared machine as in a dedicated machine?.
attendant system security requirements, the ease of administration, the adaptability toward different uses, and the different applications that will be employed. Operating System Master control program (such as DOS, Linux, MacOS, Solaris, Unix, and Windows) that automatically runs first when a computer is switched on, and remains in the background until the computer is turned off. It commonly comes preinstalled (on the boot section of the computer's main hard disk) and is usually the most complex and largest program to be used by the computer. A computer user is typically more affected by the capabilities and whims of the OS than by those of the hardware. Main services provided by an OS include user-interface, carrying out commands of the user and the application programs, supervising installation and running of other programs and hardware, controlling the input-output functions, allocating system resources such as memory, processor time, disk space, and peripheral devices to regulate the flow of work within the computer, handling file and directory management, and providing file-sharing and networking. One of the operating system's main tasks is to control the computer's resources— both the hardware and the software. The operating system allocates resources as necessary to ensure that each application receives the appropriate amount. In addition to resource allocation, operating systems provide a consistent application interface so that all applications use the hardware in the same way. This is particularly important if more than one type of computer uses the operating system or if the computer's hardware is likely to change. By having a consistent application program interface (API), software written on one computer can run on other types of computers. Developers face the challenge of keeping the operating system flexible enough to control hardware from the thousands of different computer manufacturers. http://www.businessdictionary.com/definition/operating-system-OS.html https://www.lifewire.com/operating-systems- 2625912 http://ecomputernotes.com/fundamental/disk-operating-system/what-is-operating-system https://www.pcmag.com/encyclopedia/term/48510/operating-system WHAT OPERATING SYSTEMS DO Operating systems must accomplish the following tasks:
- Processor management. The operating system needs to allocate enough of the processor's time to each process and application so that they can run as efficiently as possible. This is particularly important for multitasking. When the user has multiple applications and processes running, it is up to the operating system to ensure that they have enough resources to run properly.
- Memory storage and management. The operating system needs to ensure that each process has enough memory to execute the process, while also ensuring that one process
does not use the memory allocated to another process. This must also be done in the most efficient manner. A computer has four general types of memory. In order of speed, they are: high-speed cache, main memory, secondary memory, and disk storage. The operating system must balance the needs of each process with the different types of memory available.
- Device management. Most computers have additional hardware, such as printers and scanners, connected to them. These devices require drivers, or special programs that translate the electrical signals sent from the operating system or application program to the hardware device. The operating system manages the input to and output from the computer. It often assigns high-priority blocks to drivers so that the hardware can be released and available for the next use as soon as possible.
- Application interface. Programmers use application program interfaces (APIs) to control the computer and operating system. As software developers write applications, they can insert these API functions in their programs. As the operating system encounters these API functions, it takes the desired action, so the programmer does not need to know the details of controlling the hardware.
- User interface. The user interface sits as a layer above the operating system. It is the part of the application through which the user interacts with the application. Some operating systems, such as Microsoft Windows and Apple Macintosh, use graphical user interfaces. Other operating systems, such as Unix, use shells. TYPES OF OPERATING SYSTEMS Most simple, single-function computers (such as in microwave ovens with digital keypads) do not require an operating system. In fact, trying to implement an operating system in these computers would be overkill. On the other hand, all personal desktop and laptop computers and servers do require an operating system. While there are hundreds of operating systems available, the most popular by far are the Microsoft Windows family of operating systems, the Macintosh operating system, and the Unix family of operating systems. There are four general types of operating systems. Their use depends on the type of computer and the type of applications that will be run on those computers.
- Real-time operating systems (RTOS) are used to control machinery, scientific instruments, and industrial systems. In general, the user does not have much control over the functions performed by RTOS.
- Single-user, single-task operating systems allow one user to do one thing at a time. An example of a single-user, single-task operating system is the operating system used by personal digital assistants (PDAs), also known as handheld computers.
- Single-user, multi-tasking operating systems allow a single user to simultaneously run multiple applications on their computer. This is the type of operating system found on most personal desktop and laptop computers. Microsoft Windows, Mac OS, and Linux are three well-known examples of this type of system
QUESTION 2
A). Time-sharing is a technique which enables many people, located at various terminals, to use a particular computer system at the same time. Time-sharing or multitasking is a logical extension of multiprogramming. Processor's time which is shared among multiple users simultaneously is termed as time-sharing. Also, time-sharing system is an interactive (or hands- on) computer system that provides direct communication between the user and the system. It allows many users to share the computer simultaneously. Since each action or command in a time-shared system tends to be short, only a little CPU time is needed for each user. On the other hand, Multiprogramming is a rudimentary form of parallel processing in which several programs are run at the same time on a uniprocessor. Since there is only one processor, there can be no true simultaneous execution of different programs. Instead, the operating system executes part of one program, then part of another, and so on. To the user it appears that all programs are executing at the same time. So, in a multiprogramming and time-sharing environment, several users share the system simultaneously. This situation can result in various security problems. Two of these problems are: Copying or Stealing one’s programs or data Today, everyone depend their daily task mostly on computers. They do research; accounting; programs; create, print, delete , and search files; spend their leisure time through gaming and other activities that make computers the major requirements to attain these. In this case, in a multiprogramming and time-sharing environment where several users share the system simultaneously, there will be no assurance that each files, programs and data of each user will have the privacy or be restricted to other users especially when the user does not know how to make his files unexposed to other user. Two good examples of this situation are: when using Team Viewer or the built-in Remote Desktop Service (formerly Terminal Service). Both of them are used in the same way but differ on how they will execute. For instance the Remote Desktop Service, you can specify how many users can connect to your computer and also you can specify their limitations. Then when the user is now connected to your computer, he has the freedom on whatever he will do to your computer, whether he will create, delete or search for files. And worst, can copy and steal confidential information and data and transfer it to his computer. It is an illegal transfer of electronic data. This is possible because in a multiprogramming and time-sharing environment, you can run programs at the same time while doing a specific task. In general speaking, it is a multi-tasking activity. Using system resources (CPU, memory, disk space, peripherals) with improper accounting When there are several users using the system simultaneously, it cannot be guaranteed that there will be a specific amount of space or limitations in using system resources. As the time goes by, each user occupies a number of bytes of memory and disk space, and an amount of programs process by the CPU and the amount of time that peripherals are being used. And as the time increases, the system resources will proportionally increase their capability and production. In this case, a great possibility that there will be a shortage in memory and disk space most especially when it is not use with proper accounting or allocation. When this happens, all users sharing and connected to the system will now be interrupted and worst of it
all, their programs will crash and their paper works and the likes will not be save. But then there are solutions to ease this scenario. A good example is through virtualization which can make hosting of multiple virtualized environments within a single OS instance possible (VMware software is an example). B). Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine? We cannot ensure the same degree of security in a time-share machine as we have in a dedicated machine because time-share machine allows programs to run at the same time and allows many users to use it simultaneously. In this case, the degree of security is less compared to the security in a dedicated machine. Time-share machine has many programs to execute with and its focus has been divided to the numbers of programs as well as to the number of users using it. On the other hand, dedicated machine focuses for a specific task and programs to be executed and for this reason, this machine has the higher control compared to time-share in implementing policies regarding users’ accessibility and control to implement the degree of security. In general, any protection scheme devised by humans are expected to be broken also by humans, and as the more complex the scheme is, the more difficult it is to correct its implementation. ihttp://thumbsup2life.blogspot.co.za/2010/12/multiprogramming-and-time-sharing.html https://www.ukessays.com/essays/information-technology/multiprogramming-and-time- sharing-information-technology-essay.php http://eleonorhea.blogspot.com/2010/12/multiprogramming-time-sharing.html
