DOS Boot Configuration Ordering At initial power-on, which of the following configuration lines would be executed earlier in the DOS boot sequence (before the others)?

Introduction / Context:
During DOS boot, CONFIG.SYS directives are processed before AUTOEXEC.BAT commands. Memory managers have a specific load order: the extended memory manager (HIMEM.SYS) must load before the expanded memory manager (EMM386.EXE), and both load before environment settings in AUTOEXEC.BAT (such as PROMPT).

Given Data / Assumptions:

• Standard DOS boot with CONFIG.SYS and AUTOEXEC.BAT.
• HIMEM.SYS and EMM386.EXE appear as DEVICE= lines in CONFIG.SYS.
• PROMPT is typically set in AUTOEXEC.BAT.

Concept / Approach:
The order is: process CONFIG.SYS (DEVICE lines first) → load COMMAND.COM → run AUTOEXEC.BAT (PROMPT and other commands). Within CONFIG.SYS, HIMEM.SYS (XMS manager) must be loaded before EMM386.EXE (EMS / UMB provider) because EMM386 depends on extended memory services.

Step-by-Step Solution:
CONFIG.SYS begins processing on boot.DEVICE=c:\dos\himem.sys loads first to provide XMS services.DEVICE=c:\emm386.exe may load next to enable EMS/UMBs.After CONFIG.SYS completes, COMMAND.COM runs AUTOEXEC.BAT where PROMPT=$p$g executes.

Verification / Alternative check:
Reorder the lines and observe boot errors or warnings: EMM386 often requires HIMEM.SYS already loaded, confirming the precedence.

Why Other Options Are Wrong:
Option A (EMM386) should not load before HIMEM.SYS.Option C (PROMPT) resides in AUTOEXEC.BAT and runs later.Option D is not a standard DOS directive.

Common Pitfalls:

• Loading EMM386 without HIMEM causes instability or failure.
• Assuming PROMPT in CONFIG.SYS; it belongs in AUTOEXEC.BAT.

Final Answer:
Device=c:\dos\himem.sys