Type: System Files
Acronym: Windows System File
File used by Microsoft DOS and Windows operating systems; contains system settings and variables, as well as functions that are used to run the operating system; commonly used to store device drivers and other core Windows functions.
Some examples of SYS files include the following:
- IO.SYS: stores the default DOS device drivers and the DOS initialization program; used by DOS and Windows 9x.
- MSDOS.SYS: contains the core operating system code for DOS, known as the DOS kernel.
- CONFIG.SYS: contains the primary configuration information used by DOS.
System files are most commonly found within the Windows directory of a Windows installation. In particular, many SYS files are stored in the Windows\winsxs directory in later versions of Windows.