SYS files are generally “System” files and are widely used on Windows and MS-DOS platforms and/or systems. Most of SYS files hold executable codes that are used as hardware device drivers. Therefore, it isn’t surprising to see SYS files running in the kernel-mode which is definitely the highest possible privilege that a Windows system can give to a file. Thus, SYS files are very important and that errors in these files could bring harm on to the computer system and even data loss. Also, if SYS files are infected by malwares and viruses, it will be hard to remove them so it is very critical that users install hardware drivers that came only from the hardware manufacturer.
Two of the most notable and critical SYS files are msdos.SYS and config.SYS. These files are important because it contain configuration settings and parameters in text form and are used alongside with autoexec.BAT to control the way a computer system boots up. But then again, that was in the MS-DOS systems and is therefore obsolete. However, in the modern Windows systems, we can still use these files for backward compatibility reasons.
Nowadays, SYS files are still critical for Windows systems because Windows still use the file extension to store settings and variables to run the system itself as well as other devices or hardware and core Windows functions. The most common SYS file that can be found in the Windows systems nowadays is IO.SYS which stores default device drivers information.
Below are the programs that can open SYS files:
| Mac OS | Parallel Desktop 6 for Mac |
| Windows | Microsoft Windows 7 |
