Final

Question 1

Variable-length instructions are easier to decode than fixed-length instructions

Answer 1

False

Question 2

The best architecture for evaluating postfix notation is the stack- based architecture

Answer 2

True

Question 3

Fixed-length instructions always have the same number of operands

Answer 3

False

Question 4

One disadvantage to _______ representation is that most computers require words to be written on word address boundaries

Answer 4

big endian

Question 5

A jumpstatement is an example of a(n) _____________ instruction

Answer 5

Transfer of control

Question 6

Fixed- length instructions

Answer 6

waste space but are fast and perform better than variable length instructions

Question 7

waste space but are fast and perform better than variable length instructions

Answer 7

memory-memory, register-memory, and load-store

Question 8

Consider the postfix (reverse Polish notation) 10 5 + 6 3 - / equivalent infix expression is:

Answer 8

(10+5)/(6-3)

Question 9

Suppose the memory of a computer is as follows:

12
34
56
78

What integer value is this on a big endian computer?

Answer 9

12345678

Question 10

Suppose the memory of a computer is as follows:

12
34
56
78

What integer value is this on a little endian computer?

Answer 10

78563412

Question 11

Suppose the memory of a computer is as follows (address 100 contains the hex value CA, etc)

CA
FE
BA
BE

Assume also that these four memory locations hold one 32 - bit integer. What integer value (in hex) is this on a little endian machine?

Answer 11

BEBAFECA

Question 12

Suppose we have the instruction LDWA 800. Given memory as follows:
 800 900 
900 1000 
1000 500 
1100 600 
1200 800

What would be loaded into the accumulator if the addressing mode is immediate?

What would be loaded into the accumulator if the addressing mode is direct?

What would be loaded into the accumulator if the addressing mode is indirect?

Answer 12

800
900
1000

Question 13

very useful in matrix operations:

no great example because this category not very useful:

Word processing and normal everyday:

activities most current parallel systems:

Answer 13

SIMD
MISD
SISD
MIMD

Question 14

What is the basic computer performance equation?

Answer 14

CPU Time = seconds/program = (instructions/program) X (avg. cycles/instruction) Х (seconds/cycle)

Question 15

How do CISC and RISC machines try to achieve better performance?

Answer 15

• CISC machines reduce the number of instructions per program, and
• RISC machines reduce the number of cycles per instruction.

Question 16

What does Amdahl’s Law tell us about performance optimization?

Answer 16

Amdahl’s Law tells us that the system performance gain realized from the speedup of one component depends not only on the speedup of the component itself, but also on the fraction of work done by the component.

Question 17

What are the three primary characteristics of RISC computers?

Answer 17

• Fixed - length instructions
• high level of pipelining , and
• multiple register sets

Question 18

Why do RISC machines operate on registers?

Answer 18

This means that instructions can be executed in fewer cycles and speeds up the execution of the code, and thus the performance of the hardware. The goal for RISC architectures is single-cycle instructions.

Question 19

What does the “reduced” in reduced instruction set computer really mean ?

Answer 19

“Reduced “ originally meant providing a set of minimal instructions that could carry out all essential operations . The main objective in RISC machines is to simplify instructions so they can execute more quickly .

Question 20

Name the four primary models of computation in Flynn’s taxonomy.

Answer 20

SISD
SIMD
MISD
MIMD

Question 21

What are the three shortcomings of Flynn’s Taxonomy?

Answer 21

• There is no need for MISD machines .
• Parallelism is not homogeneous .
• There is no straightforward way to distinguish architectures of the MIMD category .

Question 22

Explain the difference between loosely coupled and tightly coupled architectures.

Answer 22

Loosely coupled and tightly coupled are terms that describe how multiprocessors deal with memory.

If there is one large, centralized, shared memory, we say the system is tightly coupled.

If there are multiple, physically distributed memories, we say the system is loosely coupled.

Question 23

What is performance benchmarking?

Answer 23

Performance benchmarking is the science of making objective assessments concerning the performance of one system over another

Question 24

What are SPEC and TPC acronyms for? How is the focus of the SPEC benchmark different from TPC benchmark?

Answer 24

SPEC is the Standard Performance Evaluation Corporation. TPC is the Transaction Performance Council.

The SPEC evaluates only CPU performance, the TPC measures the performance of the entire system.

Question 25

How can a programmer improve cache performance ?

Answer 25

• Programmers should focus on improving the reference locality
• This can be done by using cache -conscious algorithms
• or a program’s data organization and layout.