In MS-DOS maintenance, which command detects, diagnoses, and repairs logical and physical disk errors on both uncompressed and DoubleSpace-compressed drives?

Introduction / Context:
Preventive maintenance on MS-DOS systems relied on utilities that verified and repaired disks. Understanding which tool checks file system integrity, surface conditions, and supports DoubleSpace-compressed volumes is vital for restoring data access and preventing further corruption on legacy PCs.

Given Data / Assumptions:

• We are dealing with DOS 6.x era tools.
• Target functionality: detect and fix logical errors (FAT, directory) and test for physical issues; must work with DoubleSpace volumes.
• Commands listed include general maintenance utilities.

Concept / Approach:

SCANDISK performs file system checks, fixes allocation errors, cross-linked files, lost clusters, and optionally scans the surface for bad sectors. It is also aware of DoubleSpace/DriveSpace compressed volumes. DEFRAG reorganizes files to reduce fragmentation but does not repair logical errors. DBLSPACE manages compression containers; it is not a repair tool. MSAV (Microsoft Anti-Virus) scans for malware, not file system errors.

Step-by-Step Solution:

Verification / Alternative check:

Typical usage: SCANDISK C: /SURFACE verifies both logical integrity and physical media, demonstrating its intended role on DOS systems including compressed drives with the proper driver stack loaded.

Why Other Options Are Wrong:

• DEFRAG: only optimizes file placement; no structural repairs.
• DBLSPACE: creates/manages compressed volumes; not a repair utility.
• MSAV: anti-virus; unrelated to FAT/dir repairs.
• None of the above: incorrect because SCANDISK fits exactly.

Common Pitfalls:

• Running DEFRAG on a damaged file system before SCANDISK risks data loss.
• Ignoring /surface tests when intermittent read errors occur.

Final Answer:

SCANDISK.