Operating systems, application programs, and the BIOS


In this section, we will cover operating systems, application programs, and the BIOS in an effort to give you a better understanding of these essential components of the computer system architecture.


The OS

For the sake of simplicity, it is best to think of an operating system as your translator and personal assistant rolled into one. While machines are capable of incredible things they are at their core stupid and would actually have no idea what it was we were trying to get them to do if the operating system wasn’t there to translate our actions into instructions the computer can understand. They also manage all the different hardware and software and ensure every piece of harder and software can communicate with each other effectively and that everything is happening on time in the correct order necessary for things to run smoothly.

Over the years operating systems have evolved to include numerous features and services to enable it to better serve you the user. Operating systems need some sort of user interface so that the user has a way of communicating with the operating system. Two types of interface are a command line interface or a GUI which stands for ‘graphical user interface’.

Command line interfaces are very basic and consist of just a shell that the user can type commands into and receive back prompts from the machine. They have the advantage of being able to run on much lower spec machines because their lack of graphics means they need very few resources to operate. Provided a user has a good knowledge of the possible commands for their interface they can complete tasks at a much faster rate than a user that has to wait for graphical menus to load up and then navigate through. On the downside though the barrier to entry is much higher with command line interfaces as you have to really know what you are doing as opposed to a graphical interface where you can click through and see where it takes you. An example of what a command line interface might look like can be seen in the screenshot. In this example, I have given the machine the task of pinging Google to show what it might look like to use such an interface.

A GUI or graphical user interface needs a more powerful machine to operate as they are more resource heavy thanks to the graphics they contain. They usually display menu options as various graphical icons that you can click with a mouse or your finger if it is a touchscreen device. While they are slower to load and use the barrier to entry is considerably lower making them much more beginner friendly. Thanks to their ease of use graphical user interfaces are common on phones, an example of a GUI for an android phone can be seen below.

Operating systems are so important, most machines you can buy today come with one of the big three already installed. The three most popular operating systems for personal computers are Microsoft’s Windows operating system, Apple’s Mac OS X operating system and Linux which is a collection of open source operating systems that come in many different versions with everyone free to modify and distribute their own. While those are the big three in terms of personal computers the well-known Android operating system is the most popular operating system with tablets and mobile devices.

Microsoft Windows is by far the most used operating system with the large majority of personal computers having it pre-installed by default with the exception of Apple products that use Apple’s own Mac OS X.

Windows and Mac OS X

Microsoft Windows and Apple Mac OS X both tried to appeal to the largest majority of users possible by adopting a sort of ‘jack of all, master of none’ approach. Their GUI based operating systems are very user-friendly providing a very low barrier to entry for the average user. They also both have a massive number of additional features that come with their operating systems by default and while they’re never quite as good as various dedicated third-party applications that have been developed solely for a specific task they do tend to be good enough for the average user in various day to day roles.

For example, sticky notes is an application that comes with the Windows operating system by default and while it is perfectly usable as a way of managing your daily tasks it is nowhere near as good as Wunderlist, a program specifically developed solely to help you manage your tasks rather than just added to an operating system. Part of the reason behind this is that with these two operating systems trying to cover every base they have to use lightweight applications to optimize the storage requirements of their operating systems.

With security being a major issue in this day and age operating systems have evolved to be as secure as possible. A firewall, antivirus, a secure browser that can warn you about sites before you load them up and fingerprint and face recognition capabilities are just some of the security features that come with the latest Windows operating system.

Most operating systems also include applications to help the user stay organized and increase productivity. A calculator, a notepad, a sticky notes application, a calendar, a clock, and a voice recorder are all examples of this that also come with the latest version of Windows by default.

There are also a number of utility tools rolled out with both of these operating systems to assist the more knowledgeable users in cleaning up their own machines and improving performance rather than having to pay an expert to do it for them.

For instance, Windows contains a resource monitor for an in-depth analysis of your machines resource usage, a performance monitor for detailed performance reports,  a disk clean-up utility to help you free up space on the machine and a registry editor utility for those users looking to tweak their registry settings. There are all sorts of advanced performance utilities capable of defragmenting your hard drive and clearing your temporary internet files etc. in order to help users optimize the performance of their machines.


Linux differs from Windows and Mac OS X in the sense that it is not a one size fits all operating system like they are. There are many different versions of Linux each tailored to suit a specific need for a certain user base. For example, if a user was interested in moving to Linux but was worried about the fact that they’ve already got used to Windows they might want the Linux distribution known as Zorin OS which was tailored specifically to help make the transition from Windows to Linux as painless as possible.

Not every Linux version is as worried about first-time users as Zorin OS, though. Some are more technical systems serving a specific purpose. One such Linux distribution is known as Kali Linux which is heavily influenced by offensive security and is designed to serve penetration testers and people in digital forensics. As such, people implementing this version of Linux tend to either already have the knowledge required to get up and running with such a technical system or else are capable enough with computers to be able to pick it up as they go.

You can see a screenshot of Kali Linux running inside Virtualbox on my laptop below.


Application programs

Application programs, usually shortened to applications or apps, is a category used to describe top-level programs commonly developed as an additional software to be installed with various operating systems that can extend a machine’s capabilities and perform certain functions for the user or even for another application.

For example, Microsoft Office is a collection, or suite, of different application programs that can be installed on top of the Windows operating system to provide the user with additional tools for performing various tasks. Included in this suite of software tools is a word processor known as Microsoft Word that allows the user to create various text documents and a spreadsheet application known as Microsoft Excel that provides the user with the tools for creating advanced spreadsheets and performing all the various calculations you could need to with them.



The BIOS, also known as the basic input output system, is a critical part of every modern machine. The BIOS is a chip located on the motherboard containing low-level software that initially boots up all the hardware, tests everything to make sure all is correct and then passes control to the operating system if one is present. This is a useful safety procedure because if any of the settings or software is wrong you can repair or replace these settings and software before they run. If you didn’t have a BIOS, you would need the operating system to be the first thing that runs on boot up and this means if anything is wrong you can’t fix it beforehand as it’s already the first thing that boots up and nothing can boot up before it.

As well as booting up all the hardware, the BIOS also holds all the hardware configurations settings and can act as an editor for these settings should a capable user wish to customize them. An example of a BIOS on a motherboard can be seen below.