Drive letter assignment (DOS/Windows legacy): With two IDE hard drives, each having a primary and an extended partition, which drive letter is assigned to the primary partition of the second drive?

Introduction / Context:
Legacy DOS/Windows systems assign drive letters based on partition type and physical disk order. Knowing this order is essential when adding a second hard drive or planning multi-boot configurations.

Given Data / Assumptions:

• Two IDE disks are present (Disk 0 and Disk 1).
• Each disk has one primary partition and one extended partition (containing logical drives).
• No removable drives or special mappings are interfering.

Concept / Approach:

The classic assignment sequence is: primary partitions on physical disks first (in controller order), then logical drives within extended partitions, again by disk order. The first hard disk’s primary partition becomes C:. The second hard disk’s primary partition receives the next letter, which is D:. After primary partitions, the system assigns letters to logical drives, starting with those on the first disk, then those on the second.

Step-by-Step Solution:

Verification / Alternative check:

Installing a clean DOS/Windows 9x system and creating the described partitioning shows the above order in FDISK and Explorer. Documentation from the period confirms this precedence rule for primary partitions ahead of logical drives across disks.

Why Other Options Are Wrong:

• C: Reserved for the first hard disk’s primary partition.
• E: or F:: These would be assigned to logical drives after primaries, not to the second disk’s primary in this scenario.
• None of the above: Incorrect because D: is the appropriate assignment.

Common Pitfalls:

Forgetting that optical drives and card readers can shift lettering; mixing SCSI/IDE device order; assuming logical drives on Disk 0 get letters before Disk 1’s primary (not true in classic rules).

Final Answer:

D