Microprocessor buses — standard widths In classic microprocessor architecture fundamentals, how many bits are commonly used on the data bus to transfer data between the CPU, memory, and I/O devices?

Introduction / Context:
The data bus is the set of parallel conductors that carries actual data values between the central processing unit, memory, and input/output peripherals. Understanding its typical width helps learners connect processor families (8-bit, 16-bit, 32-bit) to performance and design trade-offs.

Given Data / Assumptions:

• The question refers to foundational microprocessor systems commonly taught at the introductory level.
• Many classic CPUs and peripheral chips exchange data over an 8-bit data bus.
• Higher-width buses do exist (16, 32, 64), but are not the default in entry-level discussions.

Concept / Approach:
Historically, mainstream introductory microprocessors (and their memory/I-O ecosystems) used 8-bit data buses. An 8-bit bus moves one byte per transfer, which aligns with byte-addressable memory and keeps board complexity low for teaching and simpler embedded designs.

Step-by-Step Solution:
Identify “typical/commonly used” width in early and educational systems → 8 bits.Relate to byte-sized data transfers → 1 transfer = 1 byte.Confirm alternatives → 7 and 9 bits are nonstandard; 16 bits belong to wider, costlier designs.

Verification / Alternative check:
Survey of classic microcontrollers and early CPUs (e.g., foundational teaching platforms) shows widespread use of 8-bit data buses, with memory chips and peripherals designed around byte-wide interfaces.

Why Other Options Are Wrong:

• 7 or 9: uncommon widths for general data buses.
• 16: valid for 16-bit families, but not the most common foundational width.

Common Pitfalls:
Equating address-bus width with data-bus width; these are independent. Also assuming “wider is always better,” ignoring cost and complexity.

Final Answer:
8