Mobile device basics: What is the most common direct, short-range communication method from one PDA to another PDA?

Introduction / Context:
Personal Digital Assistants (PDAs) and early handhelds often exchanged data peer-to-peer without cables. Knowing the common short-range method used historically helps in maintaining or migrating legacy devices and data.

Given Data / Assumptions:

• Context is classic PDA-to-PDA transfer (contacts, calendar, small files).
• Devices are in close proximity and likely line-of-sight.
• No docking cradle or host computer is involved.

Concept / Approach:
Infrared (IR), particularly IrDA (Infrared Data Association) standards, was the de facto method for PDA beaming. It provided simple, cable-free, line-of-sight exchange. USB and IEEE 1394 are host-centric wired buses, not typical peer-to-peer between standalone PDAs. RS-232 could be used with serial cables and cradles, but not as the main hand-held-to-hand-held wireless method.

Step-by-Step Solution:

Verification / Alternative check:
Device manuals and OS menus often include a “Beam” or “Send via IR” option for contacts and memos.

Why Other Options Are Wrong:
USB/IEEE 1394 need a host; RS-232 needs a cable and is not the common user workflow for PDA-to-PDA.

Common Pitfalls:
Blocking the IR window or misaligning devices prevents discovery; ambient sunlight can interfere.

Final Answer:
IR