WBUT Question Papers CS
Advanced Computer Architecture B Tech – 2009
Time : 3 Hours J
Full Marks : 70
GROUP-A (Multiple Choice Type Questions )
- Choose the correct alternatives for the following : 10 x 1 = 10
1) The vector stride value Is required
|a)||to deal with the length of vectors|
|b)||to find the parallelism in vectors|
|c)||to access the elements in multi-dimensional vectors|
|d)||to execute vector instruction.|
|The performance of a pipelined processor suffers if|
|a)||the pipeline stages have different delays|
|b)||consecutive instructions are dependent on each other|
|c)||the pipeline stages share hardware resources|
|d)||all of these.|
111) Consider the cache memory with access time 40 ns has the hit ratio of 80%. The regular memory has an access time of 100 ns. What is the effective access time for CPU to access memory ?
a) 52 ns b) 60 ns
c) 70 ns d) 80 ns.
CS/B.TECH (C8E)/SEM-t/CS-i03/09 4
iv) What Is a main advantage of classical vector systems ( VS ) compared to RISC based systems ( RS ) ?
a) VS have significantly higher memory bandwidth than RS
b) VS have higher clock rate than RS
c) VS are more parallel than RS
d) None of these. 1 I
v) Associative memory Is
a) pointer addressable memory
b) very cheap memory
c) content addressable memory
d) slow memory. I 1
vi) The principle of locality justifies the use of
a) interrupts b) polling .
c) DMA d) cache memory………………………………………….. 1 – , I
vll) How many address bits are required for a 512 x 4 memory ?
a) 512 b) 4
c) 9 d) Aq-Aq. I- 1
vill) The division of stages of a pipeline Into sub-stages is the basis for *
d) VLIW processor. ___
ix) What will be the speed up for a four stage linear pipeline when the number , of instruction re * 64 ?
. c) 6-5
x) Dynamic pipeline allows
a) multiple function to evaluate >
b) only streamline connection
c) perform fixed function
d) none of these. L.-—J
GROUP-B (jlhort AnswerType Questions )
Answer any three of the following questions. 3 *5 ■ 18 2. Consider the pipelined execution of these instructions :
DADD Rl, J12, R3
DSUB R4, Rl, R5
AND R6, R1.R7
XOR RIO, R1.R11
Explain how the above execution may generate a data hazard and describe a way to minimize the data hazard stalls using forwarding. Modify the above example to show a case where forwarding may not work.
- 3. Consider a computer where the clock per Instruction ( CPI ) is 10 when all memory accesses hit ( no memory stalls ) in the cache. Assume each clock cycle is 2 ns. The only data accesses are loads and stores, and these total 50% of the instructions. * ■ ‘ ‘ ‘ ‘ .
Assume the following formula for calculating execution time :
CPU execution time * ( CPU clock cycles + Memory stall cycles ) x Clock cycle time.
For a program consisting of 100 instructions :
- Calculate the CPU execution time assuming there are no misses.
. • . . *
- Calculate the CPU execution time considering the miss penalty Is 25 clock cycles and the miss rate is 2%.
Discuss the difference between write through and write back cache policies.
- 4. Assume the performance of 1 -word wide primary memory organization is
* 4 clock cycles to send the address
- 56 clock cycles for the access time per word
* 4 clock cycles to send a word of data
Given a cache block of 4 words, and that a word is 8 bytes, calculate the miss penalty and tiie effective memory bandwidth.
Re-compute the miss penalty and the memory bandwidth assuming we have
* Main memory width of 2 words
* Main memory width of 4 words
- Interleaved main memory with 4 banks with each bank 1 -word wide.
- 5. Explain the concept of .strip mining used in vector processors. Why do vector processors use memory banks ?
- 6. Discuss Flynn’s classification of parallel computers.
ii84i mum’x t ■
GROUP -C ( Long Answer Type Questions )
Answer any three of the following questions. 3×15 = 45
- 7. a) Design an arithmetic unit with variable S and 2 n-blt data Inputs A and B. The circuit generates following arithmetic operations In conjuctlon with carry In Cta.
|Draw the logic diagram.
b) What is floating point arithmetic operation ? Explain all ( addition, difference, multiplication, division ) operations with example.
c) What are logical address and physical address ? If segment no. la 8. page no. is 04, word no. Is 40. Segment no. 8 hold 30 and page no. 30 hold 019, what will be corresponding physical address ? For answer figure Is essential. 5 + 5 + 5
- 8. a) What Is I/O Interface ?
b) What are I/O us. Memory Bus and Isolated us. Memory-Mapped I/O ?
c) What are the different mechanisms of Asynchronous Data Transfer ? Explain In brief.
d) Explain DMA working principle. 2 + 3 + 5 + 5
- 9. a) What are the different pipeline hazards and what are the remedies ?
b) What Is Vector array processor ? Explain with example.
c> Describe Harvard architecture. 5 + 5 + 5
- 10. a) Apply Booth’s algorithm to multiply the two numbers +11 and -12.
- b What -is the limitation of direct mapping method ? Explain with example how it
can be Improved in set-associative mapping.
c) Use 8-bit 2’s complement integer to perform – 43 + (- 13 ).
d) What is a tri-state buffer ? Design a common bus system using tri-state buffers for two registers of 4-bits each.
e) What is serial adder ? Discuss it briefly with diagram. 3 + 4 + 3 +3 + 2
- 11. a) What are the different methods for control unit design ? Explain.
b) Write down the different addressing modes with examples. ‘
c) t What do you mean by pipeline processing ?
d) What are instruction pipeline and arithmetic pipeline ?
e) Find 2’s complement of (1 AB)16 represented in 16 bit format. 4 + 6+ 2 +2 + 1