Hack #92. Hack the MS-DOS Configuration File

Tailor DOS's CONFIG.SYS file to optimize memory use, load device drivers, and set the DOS environment.

The CONFIG.SYS file resides in the root directory of your boot drive (typically C:\) and contains commands that configure your computer's hardware components (memory use and device drivers) and operating system during bootup. The contents of the CONFIG.SYS file are read and processed before DOS loads. CONFIG.SYS is a text file you can edit with DOS EDIT.COM, Windows Notepad, or any text editor program. CONFIG.SYS is used by DOS 6.22 and earlier and Windows 95-Me, but is not used by Windows NT, 2000, XP, or 2003.

You can bypass CONFIG.SYS and AUTOEXEC.BAT files if BootKeys=1 is configured in MSDOS.SYS [Hack #91] . To use this feature, press the F5 key when you see the "Starting MS-DOS..." or "Starting Windows..." notice at startup.

You can also "walk through" and accept or reject individual CONFIG.SYS and AUTOEXEC.BAT commands by pressing the F8 key instead of F5.

Under Windows 95 through Me, a few basic CONFIG.SYS parameters are preset within the IO.SYS boot file. These are:

DOS=HIGH Device=HIMEM.SYS SETVER.EXE FILES=60
BUFFERS=30 LASTDRIVE=Z STACKS=9,256 FCBS=4

These parameters aren't nearly adequate or ideal to get a typical PC with a CD-ROM drive running efficiently, so we need to create or hack our own CONFIG.SYS file to suit our needs. A typical and often more suitable CONFIG.SYS file reads as follows:

Device=HIMEM.SYS /TESTMEM:off ...

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