Loading Device Drivers in DOS If you need to load the MOUSE.SYS device driver (a system driver variant for mouse support), in which DOS startup file should you place the directive?

Introduction / Context:
DOS distinguishes between device drivers loaded during CONFIG.SYS processing and terminate-and-stay-resident (TSR) programs often started from AUTOEXEC.BAT. Knowing where to place each component ensures the driver is available early and consumes the correct type of memory.

Given Data / Assumptions:

• MOUSE.SYS is a device-driver style mouse driver (as opposed to MOUSE.COM which is a TSR).
• Standard DOS boot with CONFIG.SYS and AUTOEXEC.BAT.
• Goal: ensure mouse services are initialized before user programs run.

Concept / Approach:
System (SYS) device drivers must be declared in CONFIG.SYS using DEVICE= or DEVICEHIGH=. This causes DOS to load the driver as part of system initialization, before COMMAND.COM runs AUTOEXEC.BAT. TSR-style drivers (e.g., MOUSE.COM) typically go in AUTOEXEC.BAT instead.

Step-by-Step Solution:
Edit CONFIG.SYS.Add a line: DEVICE=C:\MOUSE\MOUSE.SYS (path as appropriate).Optionally use DEVICEHIGH= to place the driver in upper memory if available.Reboot to activate the driver before running applications.

Verification / Alternative check:
After reboot, DOS mouse-aware programs should detect the driver. If using MOUSE.COM instead, placing it in AUTOEXEC.BAT will also provide mouse support but later in the boot process.

Why Other Options Are Wrong:
AUTOEXEC.BAT (Option B) is for TSRs and commands, not SYS device declarations.WIN.INI (Option C) is a Windows configuration file, not DOS boot-level.IO.SYS and MSDOS.SYS (Options D/E) are core system files, not user-edited loader scripts for third-party drivers.

Common Pitfalls:

• Confusing MOUSE.SYS with MOUSE.COM and placing the wrong one in the wrong file.
• Loading many drivers low and running out of conventional memory; use DEVICEHIGH when appropriate.

Final Answer:
CONFIG.SYS