System Software
The operating system (OS) controls the overall operation of the computer and provides an easier way for users to interact with the computer’s hardware and software. The operating system does not have one job, in fact, the operating system is a set of programs that utilizes every task the computer performs and manages system resources, and this includes applications, I/O management, device drivers, memory management, CPU management, and hardware. The operating system is a very critical part of the computer simply because without it, the computer is useless because it cannot function.
The operating system manages the computer’s running applications and since each program consists of at least one process, there are typically several processes running at the same time. What the operating system does is manage the computer’s resources in order to run them in an organized manner. This is called scheduling (process scheduling). There are five different states that a process can be in: new, ready, running, waiting, and terminated. The operating system helps the processor organize the processes according to their status in order to keep everything running seamlessly. The operating system operates to keep running programs working and user-ready by making it seem as though several processes are running simultaneously when in fact the available resources are being switched between the processes so quickly that is appears that they are running at the same time.
The operating system makes sure that each process has enough memory to execute the process, while also making sure that one process doesn’t interfere with the memory assigned to another process. A computer has four general types of speed: high-speed cache, main memory, secondary memory, and disk storage. The operating system must balance out the need of each process with the different types of memory available. In order to do so the operating system keeps track of what memory is being used and by whom, decides what processes are going to be loaded into memory when space becomes available, allocate and deallocate memory space as needed, and schedule the requests for memory access
However, RAM has limited capacity, so when there isn’t enough RAM for the OS to store the data and instructions, the operating system borrows space from the hard drive; this method is called virtual memory. The virtual memory creates a file on the hard drive the size that the operating system needs in order to store the running applications. This file is known as a paging file (or a swap file). Whenever the operating system needs a block of memory that isn’t RAM, the virtual memory takes a block of memory from the hard drive that hasn’t been recently used and writes it to the paging file and will then read from the paging file that the operating system needs. The virtual memory then transfers the block from the paging file and adds it to the RAM in place of the old block. This processing is called paging (or swapping). What this does is trick the application into thinking there is more memory than there really is. There are a couple reasons why you could choose to do this: to allow the use of applications that are too big for the memory installed on your computer and for multitasking. Virtual memory allows multiple programs to run at one time without having enough memory to do so. However, when the virtual memory keeps borrowing space from the hard drive it can result in thrashing, which is the excessive swapping of pages and this can slow down your computer’s performance immensely.
Each peripheral device has its own machine code and with that code is a protocol that dictates how to manage and communicate with the device. The operating system uses programs called device drivers to manage and communicate with the peripheral devices connected to the computer. Device drivers translate the peripherals machine code to a language the operating system can understand and enabling the operating system to communicate with any device connected to the computer. There are also peripheral devices that allow you to connect them to the computer and are automatically detected, needing little to no manual installation; this is known as Plug and Play (PnP). PnP requires support from various computer components which includes device hardware, system software, and drivers. PnP drivers combined with system software support provides: automatic recognition of any installed hardware, hardware resource allocation, loading of proper drivers, a programming interface for drivers to interact with the PnP system and means for drivers and applications to learn of hardware changes and take appropriate action. The functions of the PnP system makes using peripherals an effortless task, eliminating the need to ever go through a complicated manual installation again.
The operating system coordinates software by using API (application programming interface). In order for any program to run it has to be able to interact with the CPU. The CPU only understand machine code so this is where an API would come in. So that the same blocks do not appear in every program, the operating system includes an API and this is what the application software uses in order to communicate with the CPU.
BIOS (Basic Input / Output System) is a chip on the motherboard that contains a set of instructions to assist loading the operating system. Because the operating system is stored to the hard drive the processor cannot get its first instruction from it when the computer is first booted. This is where the BIOS comes in; it provides instructions to the processor telling it how to get to the operating system. The first task the BIOS executes when booted up is run a Power-On Self-Test (POST). The POST checks your computer’s hardware to ensure that everything is functioning properly before the BIOS runs the actual boot. If the POST finds an issue with the computer, since it hasn’t booted up to be able to display an error message, it will use beep codes to let you know there was an error found. There are different beep codes for different issues found on the computer. For example, if an error was found with the display memory you would hear eight short beeps. You can look up how to interpret what the beep codes mean according to the makers of your motherboards BIOS maker. The first program loaded when the computer starts is the kernel. From the time the kernel is loaded it starts managing the remainder of the boot as well as input/out requests from software, translating those requests into specific instructions for the processor and is also responsible for organizing the computer’s memory and corresponding with peripherals.
Microsoft Windows, Apple Mac OS X, and Linux are three of the more commonly known operating systems. Windows and Apple are proprietary meaning you pay for them and they are closed source, there is not modifying the source code but you’re paying for good quality. Linux, on the other hand, is open source. Meaning it’s free and you have the option to edit the source code and making these modifications to your personal preference may be what some need to have. However, I would recommend Windows. Apple is a great operating system but most programs are written primarily for Windows, Windows is extremely user friendly, and if you have an older version of Windows you can update to the newer version for free. Microsoft has done a great job with their support whenever you need it, the display, user-interface, and performance of Windows is exceptional.

References
Evans, A. Martin, K. Poat, M.A. (2014) Technology in Action. Introductory. 11th edition. http://computer.howstuffworks.com/operating-system7.htm http://www.tutorialspoint.com/operating_system/os_quick_guide.htm http://www.programmerinterview.com/index.php/operating-systems/how-virtual-memory-works/ https://en.wikibooks.org/wiki/Introduction_to_Computer_Information_Systems/System_Software http://wps.prenhall.com/bp_evans_techinaction_5/79/20368/5214262.cw/-/5214265/index.html https://msdn.microsoft.com/en-us/library/windows/hardware/ff548102(v=vs.85).aspx https://forum-en.msi.com/faq/article/what-is-the-bios-and-what-does-it-do https://en.wikipedia.org/wiki/Kernel_(operating_system)
http://www.itpro.co.uk/operating-systems/24841/windows-vs-linux-whats-the-best-operating-system