In DOS startup troubleshooting, which single function key pressed during boot bypasses both CONFIG.SYS and AUTOEXEC.BAT so that drivers and TSRs do not load?

Introduction / Context:
When a DOS system fails to boot cleanly due to a problematic driver or a terminate-and-stay-resident program, one of the fastest recovery techniques is to start without processing startup files. DOS provides a built-in keypress at boot time that skips both CONFIG.SYS and AUTOEXEC.BAT, enabling you to reach a minimal environment for diagnostics.

Given Data / Assumptions:

• The machine is booting MS-DOS or a DOS-compatible environment.
• Startup files may contain drivers, memory managers, or TSRs that cause issues.
• You want a quick bypass without editing files on disk.

Concept / Approach:
Pressing F5 during the early DOS boot process instructs the loader to ignore CONFIG.SYS and AUTOEXEC.BAT entirely. By contrast, F8 initiates a step-by-step confirmation mode, prompting you for each line in the startup files so you can selectively accept or reject entries. Therefore, if the goal is a full bypass, F5 is the correct choice.

Step-by-Step Solution:

Verification / Alternative check:
Compare the device and TSR listings using MEM /C after a normal boot versus an F5 bypass boot. You should see far fewer loaded components in the bypassed session.

Why Other Options Are Wrong:

• F8: Step-by-step confirmation, not a complete bypass.
• F4 / F1: Not assigned to this DOS boot function in standard releases.
• None of the above: Incorrect because F5 performs the bypass.

Common Pitfalls:
Pressing the key too late, assuming F8 will skip everything automatically, or forgetting that some DOS variants display only a brief window for key detection.

Final Answer:
F5