Difficulty: Easy
Correct Answer: 3 MHz
Explanation:
Introduction / Context:
This question tests basic factual knowledge about the Intel 8085 microprocessor, one of the classic 8 bit CPUs used in many educational and embedded systems. Knowing the typical clock frequency of the 8085 is important because the clock directly influences instruction execution time, throughput, and system design choices such as memory speed and peripheral timing. Many competitive exams expect students to remember the commonly used maximum clock frequency rating of the standard 8085 device.
Given Data / Assumptions:
Concept / Approach:
The Intel 8085 is typically introduced in microprocessor courses with a standard maximum clock frequency of 3 MHz. This means that the external clock can run up to 3 million cycles per second. Internally, the 8085 divides this clock to generate timing signals for machine cycles and instruction execution. Although there are variants and other microprocessors in the same family that can operate at higher speeds, the most commonly quoted maximum clock frequency for the basic 8085A device is 3 MHz, which is why that value appears frequently in exam oriented study material.
Step-by-Step Solution:
Step 1: Recall from standard 8085 datasheets and textbooks that the common version of the 8085 microprocessor operates with a maximum clock of 3 MHz.Step 2: Note that lower frequencies such as 1 MHz or 2 MHz are possible but are below the maximum rating and usually not quoted as the peak specification.Step 3: Observe that higher frequencies such as 5 MHz and 10 MHz are above the normal rating for the standard 8085A device and would require different parts or different microprocessors.Step 4: Compare each option with this remembered specification.Step 5: Conclude that 3 MHz is the correct typical maximum clock frequency used for the mainstream 8085 microprocessor device taught in undergraduate courses.
Verification / Alternative check:
A quick verification method is to think about typical instruction timings. Many references describe that an 8085 instruction cycle takes multiple clock periods and that at 3 MHz the processor can execute on the order of a few hundred thousand to around one million instructions per second, depending on the instruction mix. This performance range matches the 3 MHz rating. Furthermore, when you look at classic training kits and lab manuals for 8085 based systems, they nearly always specify a 3 MHz crystal or clock source, which reinforces the idea that 3 MHz is the correct exam answer.
Why Other Options Are Wrong:
1 MHz and 2 MHz are valid operating frequencies but they are below the standard maximum rating and therefore do not answer the question about the typical maximum clock frequency. The values 5 MHz and 10 MHz are too high for the standard 8085A device and are more appropriate to other microprocessors or special high speed variants. For basic exam questions about the 8085, 3 MHz is treated as the correct value, not 5 MHz or 10 MHz.
Common Pitfalls:
A common confusion is mixing up the 8085 with other processors such as the 8086 or later microcontrollers that can run at 5 MHz or higher. Another pitfall is remembering laboratory kits that may have been configured at a lower clock frequency for ease of observation and assuming that lower value is the maximum. To avoid these mistakes, always associate the standard 8085 microprocessor with a typical maximum clock frequency of 3 MHz when answering exam questions.
Final Answer:
The standard Intel 8085 microprocessor typically uses a maximum clock frequency of 3 MHz.
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