Chapter 6 answers

Chapter 6 Review Question Solutions
1. TRUE or FALSE? The first programmable machine was a mechanical calculator
designed by Charles Babbage.
2. TRUE or FALSE? Ada Byron is generally acknowledged as the world’s first
programmer, due to her work on Babbage’s Analytical Engine.
3. TRUE or FALSE? An electromagnetic relay is a mechanical switch that can be used to
control the flow of electricity through a wire.
4. TRUE or FALSE? Vacuum tubes, as they have no moving parts, enable the switching of
electrical signals at speeds far exceeding those of relays.
5. TRUE or FALSE? Although they were large and expensive by today’s standards, early
computers such as the MARK I and ENIAC were comparable in performance (memory
capacity and processing speed) to modern desktop computers.
6. TRUE or FALSE? Because transistors were smaller and produced less heat than vacuum
tubes, they allowed for the design of smaller and faster computers.
7. TRUE or FALSE? A microprocessor is a special-purpose computer that is used to control
scientific machinery.
8. TRUE or FALSE? Moore’s Law states that the number of transistors that can be
manufactured on a computer chip doubles every 12 to 18 months.
9. TRUE or FALSE? The first personal computer was the IBM PC, which first hit the
market in 1980.
10. TRUE or FALSE? Many Web servers improve performance by utilizing parallel
processing, in which multiple processors run simultaneously to handle page requests.
11. Mechanical calculators, such as those designed by Pascal and Leibniz, were first
developed in the 1600s. However, they were not widely used in businesses and
laboratories until the 1800s. Why was this the case?
Early calculators were difficult to build, owing to the precision required in making and
assembling all the interlocking pieces. It wasn’t until the early 1800s, when
manufacturing methods improved to the point where mass production was possible, that
mechanical calculators became commonplace in businesses and laboratories.
12. Jacquard’s loom, although unrelated to computing, influenced the development of modern
computing devices. What design features of that machine are relevant to modern
computer architectures?
Jacquard’s loom, which used metal cards with holes punched into them to specify the
weaving pattern, was the first programmable device. By changing the program (i.e., the
cards), the same loom could be used to produce different patterns. The idea of a
programmable machine was later adopted by Babbage for his Analytical Engine and
eventually led to modern, programmable computers. The use of punch cards for
representing data was also adopted by Babbage and early computer designers.
13. What advantages did vacuum tubes provide over electromagnetic relays? What were the
disadvantages of vacuum tubes?
Since vacuum tubes had no moving parts, they enabled the switching of electrical signals
at speeds far exceeding those of relays. However, vacuum tubes were expensive,
required significant power, and tended to burn out frequently.
14. As it did with many technologies, World War II greatly influenced the development of
computers? In what ways did the war effort contribute to the evolution of computer
technology? In what ways did the need for secrecy during the war hinder computer
Defense related projects provided funding for early computer research and development,
including the COLOSSUS for use in code breaking and ENIAC for computing ballistic
tables. The work of Zuse in Nazi Germany was lost during the war, and the very
existence of the COLOSSUS was top secret for decades after the war.
15. What features of Babbage’s Analytical Engine did von Neumann incorporate into his
architecture? Why did it take over a century for Babbage’s vision of a general-purpose,
programmable computer to be realized?
The von Neumann architecture takes its basic design elements from Babbage’s Analytical
Engine (although the technologies intended to implement the designs were significantly
different). Babbage’s store corresponds to memory, his mill corresponds to the CPU, and
his input/output devices (punch cards and paper tape) were not all that different from I/O
devices in von Neumann’s time. The fact that Babbage’s machine was programmable,
with the mill executing programming instructions to perform different tasks, also mirrors
the behavior of von Neumann’s architecture. In many ways, Babbage’s vision was ahead
of its time, as the technology of his day (steam power, factory production, …) was not
capable of building the intricate machinery require to complete his design.
16. It was claimed that the ENIAC was programmable, but programming it to perform a
different task required rewiring and reconfiguring the physical components of the
machine. Describe how the adoption of the von Neumann architecture allowed for
subsequent machines to be more easily programmed to perform different tasks.
The von Neumann architecture allowed for programs to be stored in memory along with
data, and executed by the CPU. Thus, the same machine could perform different tasks
simply by loading a different program into memory and executing it.
17. What is a transistor, and how did the introduction of transistors lead to faster and cheaper
computers? What other effects did transistors have on modern technology and society?
A transistor is a piece of silicon whose conductivity can be turned on and off using an
electric current. Since transistors were smaller, cheaper, more reliable, and more energyefficient
than vacuum tubes, they allowed for the production of more powerful yet
inexpensive computers.
18. What does the acronym VLSI stand for? How did the development of VLSI technology
contribute to the personal computer revolution of the late 1970s?
Very Large Scale Integration (VLSI) refers to the ability to manufacture hundreds of
thousands or even millions of transistors on an IC chip. The ability to mass-produce
computer chips that contained all of the circuitry necessary to perform tasks (e.g.,
microprocessors, RAM chips) allowed for the production of affordable, desktop
19. What was the first personal computer and when was it first marketed? How was this
product different from today’s PCs?
The first personal computer (PC), the MITS Altair 8800, was marketed in 1975. The
Altair was a computer kit that required assembly by the user, and had no keyboard, no
monitor, and no permanent storage. The user entered instructions directly by flipping
switches on the console and viewed output as blinking lights.
20. Describe two innovations introduced by Apple Computer in the late 1970s and early
The Apple II, released in 1977, was the first preassembled personal computer that
included a keyboard, color monitor, sound, and graphics. The Apple Macintosh, released
in 1984, introduced the now familiar graphical user interface of windows, icons, pulldown
menus, and a mouse pointer.
21. Each generation of computers resulted in machines that were cheaper, faster, and thus
accessible to more people. How did this trend affect the development of programming
As computers became cheaper and more accessible to companies and individuals, it was
necessary to simplify their use so that people other than engineers could manage them.
Assembly languages were the first step in making programming easier, followed by highlevel
languages that allowed non-technical people to control computer execution.
22. Two of the technological advances described in this chapter were so influential that they
earned their inventors a Nobel Prize in Physics. Identify the inventions and inventors.
John Bardeen, Walter Brattain, and William Shockley received the 1956 Nobel Prize in
Physics for their invention of the transistor. Jack Kilby received the 2000 Nobel Prize in
Physics for his work on the development of integrated circuits.