DOS Drive Letter Assignment A PC has two IDE hard drives. Each drive has a primary partition and an extended partition. Which drive letter is assigned to the primary partition of the second (slave) drive under standard DOS letter assignment rules?

Introduction / Context:
DOS assigns drive letters in a fixed order: primary partitions first (starting with C: for the first hard disk), followed by logical drives inside extended partitions, then additional physical disks. Knowing this order is essential for troubleshooting multi-drive systems.

Given Data / Assumptions:

• Two IDE drives with both primary and extended partitions.
• No removable drives or special device mappings interfere.
• Default DOS letter assignment behavior is used.

Concept / Approach:
DOS first assigns C: to the active primary partition of the first hard disk. Next, it assigns letters to any other primary partitions on additional hard disks before moving on to logical drives in extended partitions, in physical disk order.

Step-by-Step Solution:
Primary partition on Disk 1 → C:.Primary partition on Disk 2 → D: (because primaries are assigned before extended/logical drives).Logical drives inside extended partitions are assigned letters after primaries (e.g., E:, F:, etc.).

Verification / Alternative check:
Boot a DOS system with two disks and run FDISK or DIR on successive drive letters. You will observe the second disk’s primary partition appears at D: if present.

Why Other Options Are Wrong:
C (Option A) is already the first disk’s primary.E or F (Options C/D) would be assigned after D: under standard ordering.Option E is incorrect because a standard answer exists.

Common Pitfalls:

• Assuming logical drives come before additional primaries—they do not.
• Forgetting that some OEM tools or network mappings can alter letters, but not in a default DOS-only setup.

Final Answer:
D