computer organization

Question

In a hypothetical system, the read and write operations occur 40% and 60% of the times respectively. If average cycle time for read and write are 79.1 ns and 84.2 ns respectively, find the data rate of memory approximately (in mega words/sec). Assume only one word is read are written in one cycle.
 

• (A)160
• (B)150
• (C)140
• (D)170

Answer 1

Avg or expected cycle time

= 40% * 79.1 + 60% * 84.2

= 82.16 ns

 

Now, 1 word read/written $\equiv$ 1 cycle

i.e 1 word read/written $\equiv$ 82.16 ns

$\therefore$   ?  $\equiv$ 1 sec

 

Thus, answer

= $\frac{10^{9}}{82.16}$ mega-words/sec

= 12.17 megawords/sec