Table of Contents
TOC \o "1-3" \h \z \u Introduction PAGEREF _Toc401612065 \h 3Memory Management PAGEREF _Toc401612066 \h 3Process Management PAGEREF _Toc401612067 \h 5Windows PAGEREF _Toc401612068 \h 6Linux/UNIX PAGEREF _Toc401612069 \h 6MAC OS PAGEREF _Toc401612070 \h 6File Management PAGEREF _Toc401612071 \h 8Window’s Security PAGEREF _Toc401612072 \h 10MAC OS’s Security PAGEREF _Toc401612073 \h 11UNIX/Linux’s Security PAGEREF _Toc401612074 \h 11Conclusions PAGEREF _Toc401612075 \h 12References PAGEREF _Toc401612076 \h 13 TOC \h \z \c "Figure" Figure 1: System Deadlock PAGEREF _Toc401611097 \h 7 IntroductionMemory ManagementMemory Management is the process of coordinating computer memory and allocating blocks of memory for different running programs to achieve optimum performance. Memory management takes places within the hardware of a computer, the operating system, and in the programs and applications. Memory is one of the most essential components of any computer system. Regardless of which operating system is being used, whether it is Windows, Mac, Linux or UNIX, the same basic requirements of memory management exist. The main requirements of memory management are protection, sharing, relocation, and organization. Memory protection is necessary because it stops unauthorized programs, which may contain harmful threats, from accessing the computer’s memory. Memory sharing is when multiple programs need to access the same portion of memory. Proper management of memory ensures that this happens without hindering the performance of the system. Relocations is the process of moving programs between virtual memory and physical memory. To maintain optimum performance, a process will be swapped out while another process executes and then the initial process with be swapped back in, but at a different location in the memory. Organization is a key component in memory management because some blocks of memory need to be accessed quicker than others. These blocks are stored in random access memory (RAM), which is readily. The two main components of RAM are physical memory and virtual memory. Physical memory is the actual amount of memory installed on a computer and is typically 64 or 128 megabytes. This is not enough memory to run all the programs on a computer, so a technique called virtual memory is used. According to “Microsoft.com”, “Virtual memory combines your computer’s RAM with temporary space on your hard disk. When RAM runs low, virtual memory moves data from RAM to a space called a Paging file. Moving data to and from the paging file frees up RAM so your computer can finish its work” (Support – What is Virtual Memory). The concept of virtual memory is based on virtual addresses. When data is stored in virtual memory, it is assigned a virtual address that maps to a physical address. When the virtual address is called it is translated into a physical address through the use of age tables. This process of calling memory is known as paging. Now that some of the basic components of memory management have been explained, let us take a look at how each of the different operating systems manages its memory. First there is Mac. To determine the amount and allocation of memory for Mac, an activity monitor is used to display the system’s memory. Mac groups memory into four categories: free memory, wired, active and inactive. Free memory is the system’s available memory. Wired memory is used by the kernel and cannot be swapped in and out. Active is memory currently being used and inactive was recently used and stored so that it can be accessed quickly. Through the use of virtual memory, Mac allocates up to 4 gigabytes (GB) for each process. In comparison, Windows, Linux, and UNIX allocate the same amount, but specify where the 4GB will go. Windows reserves 2 GB of the 4 GB for kernel mode while Linux and UNIX allocates only 1GB for the kernel. When it comes to sharing memory, Mac OS X generally does not share memory...
References: Apple (2014). Mac OS X Security Configuration. Cupertino, CA: Author.
Mills, E. (October 2014). In their words: Experts weigh in on Mac vs. PC security. Retrieved from HYPERLINK "http://www.cnet.com/news/in-their-words-experts-weigh-in-on-mac-vs-pc-security/" http://www.cnet.com/news/in-their-words-experts-weigh-in-on-mac-vs-pc-security/
Microsoft (October 2014). About Security Management. Retrieved from http://msdn.microsoft.com/en-us/library/windows/desktop/ms721748(v=vs.85).aspx.
Stallings, W. (2015). Operating systems: internals and design principles (8th ed.). Upper Saddle River , NJ: Prentice Hall.
Tutorialspoint (2014). UNIX: File Permission/Access Modes. Retrieved from http://www.tutorialspoint.com/unix/unix-file-permission.htm.
Unknown, U. (n.d.). FreeBSD Handbook Chapter 4 UNIX Basics. Retrieved from http://www.freebsd.org/doc/en/books/handbook/permissions.html.
Windows.microsoft.com. (2014). Retrieved from http://windows.microsoft.com/en-us/windows/what-is-virtual-memory#1TC=windows-7
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