Operation Manual

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Particularities of Operating System Function

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4. Then the boot manager reads the DOS configuration file (CONFIG.SYS) and

if it contains multiple configurations, displays a menu on the screen

prompting you to choose one of them; otherwise it just reads the

configuration and loads the indicated drivers and operating system parts

from the second DOS file.

5. After the configuration file has been processed, the command interpreter

(default COMMAND.COM) is loaded and executed. The command

interpreter is a plain DOS program.

There are several differences between DOS versions from different vendors:

• MS-DOS 5.x–6.x and PC-DOS assume that their files should be the first ones

in the root folder

• MS-DOS 5.x–6.x system files have names IO.SYS and MSDOS.SYS

• PC-DOS and DR-DOS 7.x system files have names IBMBIO.COM and

IBMDOS.COM

• MS-DOS 7.x/8.0 has one large system file IO.SYS and MSDOS.SYS becomes a

configuration file

• Letter assignment order differs for different DOS versions

• MS-DOS and PC-DOS assume the boot partition as the partition to which letter

C: has been assigned

• The CONFIG.SYS command set differs for different DOS versions

• MS-DOS 7.x/8.0 starts WIN.COM instead of COMMAND.COM if the MSDOS.SYS

file includes BOOTGUI=1

• MS-DOS 8.0 cannot function as a stand-alone operating system. CONFIG.SYS

and AUTOEXEC.BAT files processing are blocked. It can only boot the

Windows operating system. A special MS-DOS 8.0 version on the Windows

Me boot disk can function as a stand-alone operating system, but a check is

built into it so that it can only be booted from a diskette

B.1.3 System and Configuration Files

Here is the DOS system files list:

• IO.SYS (mandatory for MS-DOS)

• MSDOS.SYS (mandatory for MS-DOS 5.x–6.x)

• IBMBIO.COM (mandatory for PC-DOS)

• IBMDOS.COM (mandatory for PC-DOS)

• DBLSPACE.BIN (mandatory for MS-DOS 5.x–6.2)

• DRVSPACE.BIN (mandatory for MS-DOS 6.22–8.0)

• LOGO.SYS (optional for MS-DOS 7.x/8.0)

• COMMAND.COM (optional for all DOS versions)

Configuration files list: