Ace test series

Question

A DRAM chip is designed with capacity of 512MBytes with row size of 32 bits each, one refresh operation takes one nanosecond time.Total refresh time to refresh the DRAM chip once is _______________ milliseconds.

 

My answer is 134.22 milliseconds while the answer given is 128 milliseconds.

Comments

I'm also getting 134.22 ms.

I guess they considered 2²⁰=10⁶ this gives 128 ms.

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Thank you

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can you please provide the explanation!

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Row size 32 bits = 4 bytes

$\therefore$ Total number of rows = 2⁹ * 2²⁰ / 2² = 2²⁷

Total refresh time = Number of rows * Refresh time for each row

= 2²⁷ * 10^-9 sec

= 134.22 ms.

Ref : https://gateoverflow.in/2178/gate2010-7