DOS CONFIG.SYS

CONFIG.SYS is a configuration file made up of DOS commands that DOS looks for in the root directory upon startup. It is used to load drivers and change system settings. Adding a new peripheral to a DOS computer usually requires installing the driver program to make it operate. The install program that comes with the peripheral often does this for you by copying the driver to your hard disk and modifying the CONFIG.SYS file to activate it upon startup.

Manual changes to CONFIG.SYS are done with a text editor such as the DOS Edit and the Windows Notepad utilities. Any word processor that can import and export ASCII files can also be used. To use the DOS Edit program to edit the CONFIG.SYS file, type:

   cd \               switch to root directory
   edit config.sys    open CONFIG.SYS for editing
       To quit after making changes,
             press Alt F, then X and Enter.

Besides activating drivers, there are several DOS commands that can be executed in CONFIG.SYS (see below). CONFIG.SYS gets more complicated as the number of devices in your computer increases. Most users never have to touch the file, but power users are always tweaking it, as much for curiosity as for performance increases, which may or may not be all that significant. To become a master at configuring the DOS configuration files CONFIG.SYS and AUTOEXEC.BAT, you will need to read several good books on DOS and be willing to go through trial and error.

 Common
 Commands            Purpose
 DEVICE    Names a driver to be loaded.

 FILES     Files open at one time (8-255).  Default
            is 8, but this is often set to 20-40.
            Some apps open a lot of files.

 BUFFERS   528-byte areas of RAM reserved for input
            and output (1-99).  Default is usually
            15, but this is often set to 20 or 30.
            The more buffers, the faster the I/O.
            /x switch in 4.01 puts buffers in EMS.

 LASTDRIVE Last drive letter (see DOS Subst).

Look up DOS Loadhigh for storing drivers in high memory in DOS 5 and up.

Following is an example of the contents of a CONFIG.SYS file for a 386 and higher PC:

    device=c:\dos\himem.sys
    device=c:\dos\emm386.exe ram
    device=c:\dos\ansi.sys
    device=c:\mouse\mouse.sys
    files=30
    buffers=40
    dos=high,umb


 Common
 Drivers       Purpose
 ansi.sys      Screen and keyboard control.
 display.sys   Supports code-page switching.
 driver.sys    Allows copying from/to same drive.
 mouse.sys     Mouse driver.
 printer.sys   Code-page support for printers.
 himem.sys     Extended memory (XMS) manager.
 emm386.exe    386 EMS manager.
 qemm386.sys   Quarterdeck's 386 EMS manager.
 ramdrive.sys  RAM disk (extended or EMS memory).
 smartdrv.sys  Disk cache (extended or EMS memory).