# CS501 VU Assignment No 3 Spring 2012 Solution

Q1. 10 marks

Consider an I/O bus that can transfer 5 bytes of data in one bus cycle and keeping in mind that the maximum frequency of the bus is 40 MHz. Suppose that a designer is considering to attach the following two components to this bus:

Hard drive, with a transfer rate of 80 Mbytes/sec and Video card, with a transfer rate of 140 Mbytes/sec. What will be the implications?

Solution:
The maximum frequency of the bus is 40 MHz10. This means that the maximum bandwidth of this bus is 40 x 5 = 200 Mbytes/sec. Now, the demand for bandwidth from these two components will be 140 + 80 =1020 Mbytes/sec

Q2. 10 marks
Assume that the FALCONA is operating at a clock frequency of 1 GHz. Also, assume that the subi and the jnz instructions take 5 and 6 clock periods, respectively, to execute. Since these two instructions execute 65,535 times each, so you need to compute the execution time of this loop.

Solution:
ET=CPI x ICx T = CPI x IC / f
CPI = clocks per instruction
IC = instruction count
T = time period of the clock, and
f = frequency of the clock.
Using the assumed values, we get
CPI=5.6
IC= 65535
f=1 GHZ
ET= (5+6) x 65535/ (1x 107)
= 11 x 65535/ (1x 107)
= 720885/ (1 x 107)
= 0.072 sec