Windows Operating System In details:-

• GUI base operating system. (GUI – Graphic User Interface)

Core Files of Windows 98 or Bootable Files of Windows 98

o IO.SYS o MSDOS.SYS o COMMAND.COM

These files are also very important for DOS.

IO.SYS

• IO.SYS file is a core component file of windows 98 operating system. This file contains device drivers which are built-in for printer ports, serial ports, communication ports, floppy, hard disk etc.
• IO.SYS allows the rest of the operating system and its applications to interact directly with the system hardware and the system BIOS.
• This file is hidden system and read only which is loaded in root directory (c:\).
• This is a first file which is loaded in to RAM in windows 98 and Win me.

Incase missing of IO.SYS "Error Message"	" Invalid System Disk, Replace the disk and then press any key"
Reasons of Error	- Inside the BIOS – Improper boot sequence settings. - IO.SYS file is corrupt or delete.
Solution	- Check boot sequence of the BIOS. - Check hard disk related options in BIOS. - Try to locate IO.SYS file in c:\>, if it is not there copy it from windows 98 startup desk or from other windows 98 system.

MSDOS.SYS

• This file is a read only system file, which can be editable through text editors. MSDOS.SYS file is important part of the operating system which is responsible for booting in to GUI mode.

Incase missing of MSDOS.SYS "Error Message"	Computer booting directly in to c:\> without any error message
Reasons of Error	- If windows directory corrupt. - Change in configuration of MSDOS.SYS. - MSDOS.SYS file is corrupted or deleted.
Solution	- If windows directory is corrupted, overwrite an operating system. - If it is a problem with MSDOD.SYS file, first check its configuration. - If MSDOD.SYS is missing, copy it from other windows 98 operating system computer.

COMMAND.COM

• COMMAND.COM is consider as command interpreter which responsible for display c:\>. This file contains all internal commands of DOS. If the file is missing or corrupted then it will not effect GUI booting.

CONFIGURATION FILE

Windows 98 system contains two DOS error configuration file. One is AUTOEXEC.BAT and other is CONFIG.SYS.

AUTOEXEC.BAT

• AUTOEXEC.BAT file is automatically executable batch file. This is used to load TSR programs in to RAM at the time of system startup.
• This file is used by some DOS based program to load in to RAM. If this file is deleting or renamed, normally doesn't affect windows activity. If any executable file or command place in to this file, this file executes automatically at the time of system startup.

(Note – TSR programs are loaded in to RAM & remain in to RAM until we terminate a system or switch off the system. eg. Anti Virus Program)

CONFIG.SYS

• CONFIG.SYS file is also DOS era configuration file still in use with windows 98 operating system.

• This file is used to store path of device driver & memory management files. Usually this file present in c:\> and used by some old programs & device drivers.

(Note – Device driver are small set of programs provided along with newly purchased device to make them work properly. This software given by manufactured of devices but some device automatically install in operating system without any device drivers software given by manufactures. These types of device are called plugged & play device)