एनवीएस पीजीटी सीएस 2019 पार्ट-ए
October 14, 2023Computer-Organization
October 14, 2023Computer-Organization
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Question 5
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Consider the following data path diagram.
Consider an instruction: R0 ← R1 + R2. The following steps are used to execute it over the given data path. Assume that PC is incremented appropriately. The subscripts r and w indicate read and write operations, respectively.
1. R2r, TEMP1r, ALUadd, TEMP2w 2. R1r, TEMP1w 3. PCr, MARw, MEMr 4. TEMP2r, ROw 5. MDRr, IRw
Which one of the following is the correct order of execution of the above steps?
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3, 5, 1, 2, 4
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3, 5, 2, 1, 4
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1, 2, 4, 3, 5
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2, 1, 4, 5, 3
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First the PC value has to be moved into MAR (step-3 from the given sequence), then the instruction has to be fetched(step-5 from the given sequence).
Then Temp1 is loaded with the value of R1 (step-2 from the given sequence), then the addition operation is performed by accessing the R2 value directly and adding it to Temp1 value and storing the result in Temp2 (step-1 from the given sequence).
Finally the result from Temp2 is stored in R0 (step-4 from the given sequence).
Hence the correct sequence is (3, 5, 2, 1, 4).
First the PC value has to be moved into MAR (step-3 from the given sequence), then the instruction has to be fetched(step-5 from the given sequence).
Then Temp1 is loaded with the value of R1 (step-2 from the given sequence), then the addition operation is performed by accessing the R2 value directly and adding it to Temp1 value and storing the result in Temp2 (step-1 from the given sequence).
Finally the result from Temp2 is stored in R0 (step-4 from the given sequence).
Hence the correct sequence is (3, 5, 2, 1, 4).