PC I/O Identification On a classic desktop PC, a 25-pin female D-sub connector on the rear panel typically corresponds to which interface?

Introduction / Context:
Correctly identifying legacy PC connectors is essential for troubleshooting printers, modems, and other peripherals in labs or support environments. Two look-alike ports often cause confusion: serial and parallel. This item focuses on the 25-pin female connector.

Given Data / Assumptions:

• Legacy AT/ATX PC rear panel with D-sub connectors.
• 25-pin female and 9-pin male connectors are present.
• We are concerned with typical, standards-compliant configurations.

Concept / Approach:

Standard PC parallel ports (LPT1/LPT2) use a DB-25 female connector for printer connections. Serial ports are usually DB-9 male (later PCs) or DB-25 male (earlier systems). Thus, a DB-25 female on the back is most commonly the parallel (printer) port, not a serial COM port.

Step-by-Step Solution:

Verification / Alternative check:

Check BIOS/UEFI I/O configuration for LPT1 set to a typical base address (378h) that corresponds to the DB-25 female connector.

Why Other Options Are Wrong:

“Serial port 1” (COM1) is normally DB-9 male. “COM2 port” is also serial and normally DB-9 male. “Docking” is not a rear DB-25 female. Hence, “None of the above” is unnecessary.

Common Pitfalls:

Assuming all DB-25 connectors are serial. Remember: gender matters—female DB-25 on the PC is parallel by convention.

Final Answer:

A parallel port