The .SYS file extension can be opened in any basic text editor- even Notepad. Some of the most common .SYS files that can be seen on the Windows operating system are IO.SYS, CONFIG.SYS, and MSDOS.SYS. One could open these files to peek inside, but it is strongly not recommended.
What .SYS Files Accomplish
A .SYS file, as stated earlier, is used for settings and configurations. MSDOS.SYS, as an example, contains the operating system code for DOS. This is also known as the DOS kernel, which empowers Windows users with the ability to use DOS commands, even while in the graphical user interface (GUI).
The IO.SYS file is another good example, as it is used to work with device drivers and hardware connected to a computer. The acronym IO stands for Input / Output in this situation, which directly references the common uses for device drivers.
Although it’d be interesting to see what makes a .SYS file type tick, it can be very catastrophic to open and edit these files. If something were to be put out of place, or if extra characters were added to the .SYS file, there could be a system failure as a result. For this reason, one should never open or edit .SYS files unless they are certain they know what they are doing.
For those who can’t help but be curious, Microsoft displays the contents of these files on their website. Even more interesting is the fact that Microsoft has detailed tutorials that explain how to edit .SYS files to configure the Windows environment. The MSDOS.SYS file, for example, is detailed on the Microsoft knowledge base, and directions to configure boot and drive options are listed.
There are instructions on the Microsoft website that should be followed thoroughly. One bit of important information, for example, is the fact that MSDOS.SYS must be over 1,024 bytes in size, or some programs and functionality will cease to exist at all.
If editing a .SYS file is completely necessary, be sure to pick a text editor that doesn’t insert extra characters into the file. Microsoft Word is one example of a text editor that will give programmers a headache. Instead, use something simple such as Notepad- or even a HTML editor.
Final Thoughts on .SYS Files
The average computer user will likely never have a need to work with the .SYS file. Even advanced computer users will likely have little more need than curiosity when working with a .SYS file. The configuration present in the .SYS files should never have to be edited- and therefore, it is recommended that they not be.
There are certain instances where one could benefit from editing these files, but make sure the utmost care is taken in the process- or the entire system may be crashed as a result.
