Among common legacy PC buses, which specification typically provides the fastest data transfer rate?

Introduction / Context:
System expansion buses evolved from ISA to VESA Local Bus (VLB) and then to PCI, each offering higher throughput and better bus management. Identifying the fastest among these common standards helps in understanding why PCI displaced earlier buses in mainstream systems.

Given Data / Assumptions:

• ISA: 8/16-bit, slow clock, non-bursting transfers.
• VLB: Tied to CPU local bus, faster than ISA but less stable and less portable.
• PCI: 32-bit 33 MHz baseline (133 MB/s) with advanced features and scalability.

Concept / Approach:
While VLB can approach high raw throughput on certain 486 systems, PCI standardized higher sustained bandwidth with bus mastering, burst transfers, and better arbitration across diverse platforms. In general PC exam contexts, PCI is considered the fastest and most capable among ISA, VLB, and PCI, especially due to its widespread 133 MB/s baseline and later extensions (64-bit/66 MHz).

Step-by-Step Solution:

Verification / Alternative check:
Motherboard manuals and historical benchmarks show PCI devices outperform ISA/VLB in sustained transfers, especially for storage and networking.

Why Other Options Are Wrong:

• ISA: Oldest and slowest among the three.
• VL bus: Faster than ISA but less capable and short-lived; typically not faster overall than standardized PCI implementations.
• All of the above: Cannot all be “fastest.”

Common Pitfalls:
Confusing theoretical burst peaks with overall sustained, stable throughput across platforms.

Final Answer:
PCI