Hardware Reference
In-Depth Information
PROBLEMS
1.
Explain each of the following terms in your own words:
a. Translator.
b. Interpreter.
c. Virtual machine.
2.
Is it conceivable for a compiler to generate output for the microarchitecture level in-
stead of for the ISA level? Discuss the pros and cons of this proposal.
3.
Can you imagine any multilevel computer in which the device level and digital logic
levels were not the lowest levels? Explain.
4.
Consider a multilevel computer in which all the levels are different. Each level has in-
structions that are
m
times as powerful as those of the level below it; that is, one level
r
instruction can do the work of
m
level
r
1 instructions. If a level-1 program requires
k
seconds to run, how long would equivalent programs take at levels 2, 3, and 4, as-
suming
n
level
r
instructions are required to interpret a single
r
+ 1
instruction?
5.
Some instructions at the operating system machine level are identical to ISA language
instructions. These instructions are carried out directly by the microprogram or hard-
ware rather than by the operating system.
−
In light of your answer to the preceding
problem, why do you think this is the case?
6.
Consider a computer with identical interpreters at levels 1, 2, and 3. It takes an inter-
preter
n
instructions to fetch, examine, and execute one instruction. A level-1 instruc-
tion takes
k
nanoseconds to execute. How long does it take for an instruction at levels
2, 3, and 4?
7.
In what sense are hardware and software equivalent? In what sense are they not equiv-
alent?
8.
Babbage's difference engine had a fixed program that could not be changed. Is this es-
sentially the same thing as a modern CD-ROM that cannot be changed? Explain your
answer.
9.
One of the consequences of von Neumann's idea to store the program in memory is
that programs can be modified, just like data. Can you think of an example where this
facility might have been useful? (
Hint
: Think about doing arithmetic on arrays.)
10.
The performance ratio of the 360 model 75 was 50 times that of the 360 model 30, yet
the cycle time was only five times as fast. How do you account for this discrepancy?
11.
Two system designs are shown in Fig. 1-5 and Fig. 1-6. Describe how input/output
might occur in each system. Which one has the potential for better overall system per-
formance?
12.
Suppose that each of the 300 million people in the United States fully consumes two
packages of goods a day bearing RFID tags. How many RFID tags have to be pro-
