Why is a bus hierarchy needed?

A single bus with many devices becomes slow and overloaded

It reduces the number of devices

What is a benefit of using bridges between buses?

All buses run at the same speed

Traffic from all devices is mixed

Arbitration becomes unnecessary

2071 Chaitra · 2 marks

Need for bus hierarchy

Short answer

A single shared bus becomes a bottleneck as more devices are added, increasing propagation delay and contention. A hierarchy with local, system, and expansion buses joined by bridges lets each bus run at its optimal speed, separates fast CPU-memory traffic from slow I/O, and boosts overall performance.

Why is a bus hierarchy required?

A bus hierarchy is needed because a single bus connecting many devices becomes slow and overloaded. The extra devices increase propagation delay and the contention for the bus, and slow devices hold up fast ones. By using a local bus for the CPU and cache, a system bus for memory, and expansion buses for I/O, joined by bridges, each bus can run at the speed suited to its devices, traffic is separated, and overall performance improves.

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