Question 1

DOS Startup Files: AUTOEXEC.BAT vs CONFIG.SYS  Which statement correctly describes the role and timing of AUTOEXEC.BAT during a standard DOS boot sequence?

Accepted Answer

Introduction / Context: A classic DOS boot sequence processes two well-known startup files: CONFIG.SYS and AUTOEXEC.BAT. Knowing the order and purpose of these files is fundamental for troubleshooting device-driver issues, memory management, and environment configuration on legacy systems. Given Data / Assumptions: DOS loads system kernels first (IO.SYS and MSDOS.SYS) before user-editable startup files. CONFIG.SYS contains DEVICE and memory manager directives. COMMAND.COM loads and then runs AUTOEXEC.BAT to set user environment and TSRs. Concept / Approach: CONFIG.SYS is processed first to load low-level drivers (for example, HIMEM.SYS, EMM386.EXE) and to set system limits. Afterward, the shell (COMMAND.COM) starts and executes AUTOEXEC.BAT. This second file typically sets PROMPT, PATH, and launches terminate-and-stay-resident utilities (mouse, keyboard, network logins, etc.). Step-by-Step Solution: System powers on → BIOS POST completes.Boot sector loads IO.SYS and MSDOS.SYS.DOS reads CONFIG.SYS and loads device drivers and managers.DOS loads COMMAND.COM (command interpreter).COMMAND.COM then executes AUTOEXEC.BAT to finalize the user environment. Verification / Alternative check: Temporarily rename AUTOEXEC.BAT and reboot; devices from CONFIG.SYS still initialize, but environment variables and TSRs do not load, demonstrating that AUTOEXEC.BAT runs after CONFIG.SYS. Why Other Options Are Wrong: Option B: AUTOEXEC.BAT does not contain Windows configuration files; those are managed separately (e.g., WIN.INI, SYSTEM.INI in Windows versions).Option C: AUTOEXEC.BAT is not the same as CONFIG.SYS; they have different purposes and formats.Option D: There is no concept of “system polarity” in DOS startup files. Common Pitfalls: Loading TSRs in CONFIG.SYS rather than AUTOEXEC.BAT. Expecting PATH or PROMPT to be active before COMMAND.COM executes AUTOEXEC.BAT. Confusing Windows startup with DOS startup processes. Final Answer: Is run after config.sys on system boot-up

Question 2

Warm Boot (Soft Reset) on IBM-PC Compatible Keyboards  Which key combination triggers a warm boot without cutting system power?

Accepted Answer

Introduction / Context: A warm boot (also called a soft reset) restarts the computer without cycling the power supply. On IBM-PC compatibles, technicians and users commonly use a keyboard shortcut to invoke this process, which reinitializes the system while preserving power to components. Given Data / Assumptions: Standard PC-compatible hardware and BIOS behavior. Keyboard controller recognizes specific key sequences. Operating system permits handling or intercepting the sequence as appropriate. Concept / Approach: The keyboard controller and BIOS cooperate to interpret Ctrl+Alt+Del as a request to perform a warm boot. This restarts POST-level initialization in many legacy systems without cutting power, contrasting with a cold boot that occurs when power is first applied or physically cycled. Step-by-Step Solution: Press and hold Ctrl.Press and hold Alt.Press Del once while holding Ctrl and Alt.System performs a soft reset, restarting the boot sequence. Verification / Alternative check: On many DOS or early Windows systems, invoking Ctrl+Alt+Del immediately begins the reboot process. Modern OSes may intercept it with a security/Task Manager dialog, but the underlying intention remains tied to the warm-boot concept. Why Other Options Are Wrong: Ctrl+ESC (Option A) typically opens a Start menu or shell function; it does not reboot.Ctrl+Shift+Del (Option C) and Ctrl+Shift+Enter (Option D) are not defined as universal warm-boot triggers.Option E is incorrect because there is a well-known combination. Common Pitfalls: Confusing OS-level actions (like opening Task Manager) with firmware-level warm boot. Assuming behavior is identical on all modern systems where OS security may intercept the sequence. Final Answer: Ctrl+Alt+DEL

Question 3

DOS Media Utilities: Comparing Two Floppy Disks  Which DOS command is specifically used to compare the contents of two floppy disks?

Accepted Answer

Introduction / Context: DOS provides several floppy-disk utilities. Two that are often confused are DISKCOPY and DISKCOMP. Understanding the difference between copying and comparing is essential when verifying backups, diagnosing media issues, or validating duplication work on legacy systems. Given Data / Assumptions: Working DOS environment with two floppy drives or the ability to swap disks. Goal is to verify whether two disks contain identical data, sector by sector. Commands must be run from the DOS prompt. Concept / Approach: DISKCOMP compares the contents of two floppy disks and reports any differences. DISKCOPY, by contrast, creates a duplicate of a disk (source → destination). FORMAT prepares a disk and does not compare contents. Step-by-Step Solution: Insert source disk in drive A: and target disk in drive B:.Run DISKCOMP A: B: to compare sector contents.Review output for messages indicating identical disks or listing sectors that differ. Verification / Alternative check: To ensure a good clone, first use DISKCOPY A: B: and then run DISKCOMP A: B: to verify equality, especially when data integrity is critical. Why Other Options Are Wrong: DISKCOPY (Options A and C variants) copies; it does not compare.FORMAT A: B: (Option D) is invalid syntax and unrelated to comparison. Common Pitfalls: Assuming a successful copy implies correctness; always verify with DISKCOMP when needed. Using file-level comparison utilities can miss structural disk differences versus sector-level checks. Final Answer: DISKCOMP

Disk Operating System (DOS) Questions