Java Reference
In-Depth Information
of this chapter outlines what a program is and how instructions in a Java program
are executed by the computer.
The livetext ProgramLive
This text is accompanied by a CD, which is totally different from CDs that
accompany other texts. This CD, our original livetext ProgramLive , has on it a
multi-media version of this text. It has “lesson pages”, which are like the pages
of a topic. But each page contains several recorded mini-lectures with synchro-
nized animation —there are over 250 such lectures. You can learn from these lec-
tures, or activities as they are called, far better than you can from the static paper
that you are now reading because the CD uses time, color, animation, and a
recorded voice to enhance the presentation. The CD also contains a hypertext
index and a glossary that is unmatched in any paper programming text, includ-
ing this one.
In the left margin of the pages of this paper text, occasionally you will see
an oval with an activity number in it, or a rectangular box, like the one in the left
margin of the previous paragraph. The oval and rectangle point out material in
the livetext that may be of interest to you. Often, it explains the same material,
but in a more interesting and lively way. Make the CD an integral part of your
learning experience.
Tip: The first
lesson in the
livetext (the
CD) explains
how to use the
CD. You will
miss a lot if
you do not read
Computer organization
Twenty years ago, the internet did not exist, and most new computer science stu-
dents had never used a computer. Back then, typical programming texts began
with instructions on how to use a computer: how to turn it on, how to open a file,
how to save, how to make a backup copy. No longer. Today, most students in
most of the world are quite comfortable navigating the web.
Still, most students have never opened up a computer or really thought about
what is inside. In this section, we describe the major pieces and how information
is stored.
We can view a personal computing system as consisting of the items shown
in Fig. 0.1, which can be classified as follows:
1. The Central Processing Unit, or CPU. This is the core of the computer.
2 . Memory. Contains data that the computer is processing. This data is lost
when the computer is turned off.
3. Hard drive. Long-term data is kept here. The data is generally not lost
when the computer is turned off.
4. Peripheral units: a keyboard, monitor, mouse, printers, scanners,
CD/DVD units, cameras, small storage devices like floppy disks and zip
disks, and more.
5. Ethernet and wireless connections to the internet and networks.
This view of a computer has not changed much in the past 40 years, although
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