A dynamic RAM has a memory cycle time of 64 nsec. It has to be refreshed 100…
2005
A dynamic RAM has a memory cycle time of 64 nsec. It has to be refreshed 100 times per msec and each refresh takes 100 nsec. What percentage of the memory cycle time is used for refreshing?
- A.
10
- B.
6.4
- C.
1
- D.
.64
Attempted by 30 students.
Show answer & explanation
Correct answer: C
Key idea: compute the total time spent refreshing in 1 millisecond, then express it as a percentage of 1 millisecond.
Compute total refresh time per millisecond: 100 refreshes × 100 ns per refresh = 10,000 ns.
Convert 1 millisecond to nanoseconds: 1 ms = 1,000,000 ns.
Calculate the percentage: (10,000 ns / 1,000,000 ns) × 100% = 1%.
Answer: 1% of the memory time is used for refreshing.
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