Difficulty: Easy
Correct Answer: 3
Explanation:
Introduction / Context:
Classic microprocessors, including the Intel 8085, are described in terms of their system buses. Each bus plays a distinct role in moving addresses, data, and control information between the CPU and memory or peripherals.
Given Data / Assumptions:
Concept / Approach:
Microprocessors typically expose three external buses: an address bus (unidirectional from CPU), a data bus (bidirectional), and a control bus (signals such as RD, WR, ALE, IO/M). Knowing the count and directionality is basic to understanding memory maps and peripheral interfacing.
Step-by-Step Solution:
List the buses: address, data, control.Address bus carries location information to select memory or I/O registers.Data bus carries operand and result bytes both to and from the CPU.Control bus coordinates timing and read/write strobes.
Verification / Alternative check:
Any 8085 block diagram shows these three grouped signal sets explicitly, confirming the total as three.
Why Other Options Are Wrong:
2 or 4 or more than 3: do not match the standard external organization for the 8085.
5 or 8: exceed the canonical grouping, confusing individual lines with bus categories.
Common Pitfalls:
Counting internal paths or individual control lines as separate buses. The conventional answer groups signals into the three system buses.
Final Answer:
3
Discussion & Comments