In the classification of computer generations, microprocessors used as switching and processing devices are characteristic of which generation of computers?

Introduction / Context:
Computer history is commonly divided into generations based on the main technology used for switching and processing. First generation computers used vacuum tubes, second generation used transistors, third generation used integrated circuits and fourth generation introduced microprocessors. Understanding which technology belongs to which generation is a standard topic in computer awareness exams.

Given Data / Assumptions:

• The question specifies microprocessors as switching devices.
• We must match this with the correct generation of computers.
• Options list first, second, third, fourth and fifth generation computers.
• We assume the widely accepted classification used in textbooks.

Concept / Approach:
Microprocessors are single chips that integrate the functions of a CPU. The introduction of microprocessors in the early 1970s marks the beginning of the fourth generation of computers. Before that, third generation machines used integrated circuits with multiple components on a board but not full CPUs on a single chip. First generation used vacuum tubes and second generation used transistors. Fifth generation refers to advanced technologies such as artificial intelligence and parallel processing, not specifically to the first appearance of microprocessors.

Step-by-Step Solution:
Step 1: Recall the sequence of technologies by generation. Step 2: First generation: vacuum tubes. These were large, power hungry devices. Step 3: Second generation: transistors replaced vacuum tubes and made computers smaller and more reliable. Step 4: Third generation: integrated circuits ICs combined many transistors on a single chip but typically not an entire CPU. Step 5: Fourth generation: microprocessors integrated a complete CPU onto a single chip, making personal computers possible. Step 6: Because the question explicitly mentions microprocessors, we identify the fourth generation as the correct one. Step 7: Fifth generation is often associated with future oriented ideas like AI and massively parallel processing, not the introduction of microprocessors.

Verification / Alternative check:
Computer history chapters in standard textbooks clearly label microprocessor based systems as fourth generation computers. They mention the introduction of the Intel 4004 and subsequent microprocessors as key milestones. The same chapters list vacuum tube based ENIAC and UNIVAC as first generation, transistor based systems as second generation and IC based minis and mainframes as third generation. This consistent mapping supports choosing fourth generation computers when microprocessors are referenced.

Why Other Options Are Wrong:
First generation computers predate transistors and microprocessors and relied on vacuum tubes. Second generation computers used discrete transistors but did not integrate them into single chip CPUs. Third generation moved to integrated circuits, but still at the board level rather than full microprocessors. Fifth generation aims at advanced AI and new architectures; microprocessors are already standard by then and do not define the generation itself. Therefore, only fourth generation correctly matches microprocessors as switching devices.

Common Pitfalls:
Students sometimes confuse integrated circuits and microprocessors because both involve chips. To avoid this, remember that integrated circuits refer to any chip containing multiple components, while a microprocessor is a special chip that contains an entire CPU. The appearance of microprocessors marks a clear shift to smaller, cheaper and more powerful systems, which is why it defines the fourth generation of computers.

Final Answer:
Microprocessors as switching devices are characteristic of fourth generation computers.