CONFIG.SYS
computer file
CONFIG.SYS is the configuration file for the DOS and OS/2 operating systems that specifies startup options – options that cannot be changed after the system has booted. The data it contains is read by the system and used to configure many aspects including memory management, peripherals and applications. Each line can contain a name-value pair that is either a directive that sets the value of a system setting or with name "DEVICE" extends system capability by loading a file such as a device driver or a terminate-and-stay-resident (TSR) program. CONFIG.SYS was introduced with DOS 2.0.
As Windows technology diverged from DOS over time, use of CONFIG.SYS diminished. Both CONFIG.SYS and AUTOEXEC.BAT are in the root folder of the Windows 95 and Windows 98 boot drives, but typically, they are empty. Windows Me does not use a CONFIG.SYS file at all. Instead, it loads environment variables from the Windows Registry key: HKLM\System\CurrentControlSet\Control\SessionManager\Environment.
Use
User maintained
The file is maintained by a user in order to control the behavior of the system. As an ASCII text file, a user generally edits it via a text editor.
The public source identifies “CONFIG.SYS” as computer file. This brief keeps that definition visible, then builds a research path around CONFIG, computer and file.
Why this record matters
A short description can identify a subject without explaining its stakes. For “CONFIG.SYS”, the useful work is to connect “computer file” to the records capable of establishing context and consequence.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 4, 2026. The linked authority identifier is Q1079369. None of the 0 selected statements returned an explicit reference.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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Three-step research path
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Questions for further research
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This entry incorporates text from “CONFIG.SYS” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.