DOS device drivers: Match the driver HIMEM.SYS to its correct function in classic DOS/Windows environments.

Introduction / Context:
Legacy DOS systems relied on CONFIG.SYS drivers to extend memory functionality. Two commonly confused components are HIMEM.SYS (extended memory) and EMM386.EXE (expanded memory emulation). Correct identification helps when tuning memory for older software.

Given Data / Assumptions:

• System is MS-DOS or early Windows (real/standard mode) era.
• HIMEM.SYS is loaded via CONFIG.SYS.
• We differentiate extended vs. expanded memory services.

Concept / Approach:

HIMEM.SYS is the XMS (Extended Memory Specification) manager. It enables access to memory above 1 MB (beyond the 1 MB real-mode barrier) using the High Memory Area (HMA) and extended memory blocks. EMM386.EXE, by contrast, uses the 80386’s paging to emulate EMS (Expanded Memory Specification) from extended memory. ANSI.SYS handles terminal features; code page switching is managed by DISPLAY.SYS/KEYB and related utilities.

Step-by-Step Solution:

Verification / Alternative check:

Examining CONFIG.SYS lines and boot messages shows “HIMEM is testing extended memory.” DOS utilities like MEM display XMS availability when HIMEM.SYS is active.

Why Other Options Are Wrong:

• ANSI terminal emulation: Provided by ANSI.SYS.
• Uses expanded memory on a 80386: That is EMM386.EXE, not HIMEM.SYS.
• Code page switching: Managed by internationalization drivers, not HIMEM.SYS.
• None of the above: Incorrect; the extended memory management description is correct.

Common Pitfalls:

Confusing XMS with EMS; forgetting load order (HIMEM.SYS before EMM386.EXE); overlooking that some programs require EMS specifically.

Final Answer:

Manages the use of extended memory