Viewing resident programs in DOS Which single command at the DOS prompt quickly shows memory usage and currently loaded TSRs (Terminate-and-Stay-Resident programs)?

Introduction / Context:
Terminate-and-Stay-Resident programs (TSRs) and device drivers occupy precious conventional and upper memory in DOS. When applications fail due to low memory or conflicts, technicians inspect memory maps to identify what is loaded and where. DOS provides a built-in diagnostic for this purpose.

Given Data / Assumptions:

• The user is at a DOS prompt.
• Goal: list memory blocks and identify TSRs/device drivers.
• Common DOS utilities include MEM and MEMMAKER.

Concept / Approach:

The MEM utility displays a memory summary. With switches like /C or /D, it lists conventional, upper, and high memory usage along with the modules occupying them. Even without switches, MEM presents useful totals, and technicians often start there before drilling down.

Step-by-Step Solution:

Verification / Alternative check:

Cross-check MEM results against CONFIG.SYS and AUTOEXEC.BAT. Each loaded driver or TSR should correspond to an entry, confirming the utility’s accuracy.

Why Other Options Are Wrong:

a: “Memory” is not a DOS command.

c: SYS is used to make a disk bootable; /M is not a standard switch for listing TSRs.

d: MEMMAKER optimizes memory usage interactively; it does not simply display current TSRs.

e: Not applicable because MEM is correct.

Common Pitfalls:

Forgetting to use switches (/C or /D) for module listings; misreading UMB versus HMA; assuming MEMMAKER is harmless—always back up before optimization.

Final Answer:

MEM