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?
-
AIs run after config.sys on system boot-up
-
BContains all Windows configuration files
-
CIs also known as config.sys
-
DChecks for system polarity
-
ENone of the above
Answer
Correct Answer: Is run after config.sys on system boot-up
Explanation
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