PC hardware fundamentals — Standard I/O base address for COM2 (serial port 2) In classic IBM-PC compatible systems, what hexadecimal base I/O address is assigned to COM2 by default?

Introduction / Context:
Legacy PC hardware maps serial ports (COM ports) to fixed I/O base addresses and interrupts. Knowing these defaults is crucial when troubleshooting device conflicts, configuring BIOS/UEFI options, or working with low-level drivers and embedded systems that still expose UARTs.

Given Data / Assumptions:

• IBM-PC compatible environment using the classic 16550-class UARTs.
• Default factory mappings are assumed (no custom remapping).
• Question asks specifically for the base I/O address of COM2.

Concept / Approach:

Historically, DOS/Windows and BIOS conventions standardized serial port resources to avoid conflicts. Each COM port is assigned a base I/O address plus an IRQ. Software and drivers expect these defaults unless changed in firmware or by jumpers on older multi-I/O cards.

Step-by-Step Solution:

Verification / Alternative check:

Checking any PC hardware reference, BIOS setup screens from the era, or serial card silkscreens confirms these standard addresses. Device Manager on older Windows systems also shows these defaults when resources are set to “Auto.”

Why Other Options Are Wrong:

3F8h is COM1, 3E8h is COM3, 2E8h is COM4, and 330h is not a COM base (often used by certain legacy peripherals like SCSI host adapters or game/MIDI ports, not standard serial).

Common Pitfalls:

Confusing COM1 and COM2 addresses; assuming PCI Plug-and-Play always keeps legacy defaults; forgetting that USB-serial adapters do not use I/O port addresses in the same way.

Final Answer:

2F8h.