Intel 8085A architecture — how many buses are part of the microprocessor? In the 8085A microprocessor system, count the distinct buses that connect and organize data flow (consider address, data, and control classifications).

Introduction / Context:
Classic microprocessors such as the Intel 8085A organize external communication via buses. Differentiating the address, data, and control buses clarifies how the CPU selects devices, transfers data, and orchestrates timing. This fundamental partitioning appears across many 8-bit families and remains relevant in microcontroller bus matrices today.

Given Data / Assumptions:

• 8085A exposes an address bus, data bus, and a set of control/status lines.
• Some pins are multiplexed (AD0–AD7) but logically belong to the address/data buses at different times.
• We count logical buses, not pin counts.

Concept / Approach:
The 8085A uses a 16-bit address bus (A8–A15 plus multiplexed AD0–AD7), an 8-bit data bus (AD0–AD7 during data phase), and control/status lines (RD, WR, IO/M, ALE, READY, etc.) that form the control bus. Thus there are three buses: address, data, and control. Multiplexing does not reduce the count of logical buses; it only saves pins by time-sharing functions.

Step-by-Step Solution:

Verification / Alternative check:
Any 8085A block diagram shows three labeled bus groups. The ALE signal demultiplexes AD lines to separate address and data externally.

Why Other Options Are Wrong:

• 2 buses: ignores the control bus.
• 5 or 8 buses: overcounts; sub-groups are not separate buses at the architectural level.
• 4 buses: no standard fourth bus exists in the basic 8085A memory/IO interface.

Common Pitfalls:

• Confusing physical multiplexing with the logical bus count.

Final Answer:
3