Digital communication basics — parallel vs. serial Why is parallel data transmission generally preferred over serial transmission in many short-distance digital system applications?

Introduction / Context:
Parallel and serial are two fundamental methods of moving digital data between subsystems. This question checks conceptual understanding of why parallel transmission is often chosen inside a device or over very short distances, such as between a microprocessor and memory or peripheral buses on a PCB.

Given Data / Assumptions:

• Comparison is for typical short-run interconnects on a board or backplane.
• Signal integrity and skew are manageable over short distances.
• Clocking or strobing is available to coordinate transfers.

Concept / Approach:

Parallel transmission uses multiple conductors to carry several bits simultaneously (often 8, 16, 32, or more). Serial sends bits sequentially over one pair. For a given edge rate and clock, parallel buses can deliver a higher aggregate throughput because multiple bits traverse per cycle.

Step-by-Step Solution:

Verification / Alternative check:

Historical buses (e.g., classic memory buses, PCI) used wide parallel paths to achieve high bandwidth before differential high-speed serial links matured. Even today, internal memory interfaces (like DDR) remain parallel for extreme bandwidth per pin group.

Why Other Options Are Wrong:

• It is much slower: incorrect; parallel is typically faster at short distances.
• It is cheaper: extra traces, pins, and connectors usually increase cost.
• More people use it: popularity does not determine technical preference.
• It avoids clocking altogether: parallel buses still require timing references or strobes.

Common Pitfalls:

• Overgeneralizing: over long distances, crosstalk and skew make serial preferable.
• Ignoring signal integrity: as speeds rise, parallel timing skew can limit scalability.

Final Answer:

It is much faster.