Java Software Solutions
1. Computer Processing
A computer system is made up of hardware and
Hardware: Chips, keyboards, disks, wires, etc.
Software: Programs and the data those programs use.
Key Components of a Computer System
central processing unit (CPU)
input/output (I/O) devices
secondary memory devices
Programs and data are held in storage devices called memory,
which fall into two categories:
Main Memory (“primary memory,” “central memory”…)
The storage device (e.g., chips on the mother board) that holds the
programs and their data (software) while the programs are
Devices such as hard disks that store software in a relatively
We save our software on secondary memory. Copies of the
software are brought into main memory when we execute our
Copies = data and programs
We will be concerned with two categories of software.
The operating system.
Provides a user interface that allows us to interact with the
machine (enter input and view output).
Manages computer resources such as the CPU and main
Provides protection, and much more.
Generic term for just about any software other than the
Word processors, spreadsheets (office tools), web browsers,
games, hosts of search engines, twitter, facebook, …etc.
Scientific applications; business / commercial applications…
The focus of this course is development of high-quality
application programs to be used in business / commercial
What This Means to Us
We will be learning to create application
programs using the Java programming
We will be using an IDE called NetBeans.
Current version of NetBeans is 6.7 but 5.0 and 5.5
should both be sufficient also.
IDE stands for Integrated Development
Environment. (Know this)
There are many IDEs ‘out there.’
More: What this means to us
You will download and install the J2SE
Standard Edition and Development Kit JDK
and NetBeans 6.7 (bundled together) from
links on my web page.
See: Link to Download NetBean and Java.
See the link on my web page and instructions
to download and install NetBeans 6.7 and the
See NetBeans Tutorial and Project0 Details are
See also the tutorial on how to use NetBeans
6.7 to develop and submit Project0. 6/73
Analog versus Digital Signals
Analog information and/or signals are continuous,
varying in direct proportion to the source of the
information – like the amplitude of a wave may vary
with volume. It’s period may vary with frequency…
(Hz (frequency) measured in cycles per second; Period is
seconds per cycle)
Digital technology breaks information into discrete
pieces and represents the pieces as numbers.
Music on a CD is stored digitally, as a series of numbers.
The music is sampled about 40,000 times per second and
each number represents the voltage level of one specific
instance of the recording.
An Analog Signal
versus a Digital Signal
1 0 1 0 0 1 …
A digital computer stores information as
numbers: ones and zeroes.
These numbers represent ‘state’
On/off; one/zero, etc.
All information in a computer is stored and
managed as binary values.
The binary number system has only two digits, 0
A single binary digit is called a bit.
Converting Binary Numbers
to Decimal Numbers
Starting with the rightmost bit in a binary number,
each position represents a power of 2, with the
rightmost bit position representing 20 which is decimal
1, the next bit position representing 21 which is 2 and
the next representing 22 which is 4, etc.
Binary 1011 is 1* 23 or 8 + 0 * 22 or 0 + 1 * 21 or 2 + 1 *
20 or 1 which adds up to 11 decimal (base 10).
Binary 11001001 is 201 decimal.
CAN YOU DO THIS???? Yes, you need to know this!
In general, n bits can represent 2n unique items.
Computers typically manipulate sequences of 8 bits
with each sequence of 8 bits referred to as a byte.
2. Hardware Components
We use the term computer architecture to describe how
the hardware components of a computer are put together.
A program and its data reside in main memory while the
The Central Processing Units (CPU) reads one program
instruction from main memory and executes it.
(Called ‘fetch – execute’ cycle)
If an instruction needs data, such as the amount in a bank
account, the CPU will acquire that information from central
memory (which may require the access of data in secondary
memory to be brought into memory first).
The process repeats until the program ends.
Almost all devices in a computer other than
the CPU and main memory are called
Controllers are devices that coordinate the
activities of specific peripherals.
A unit with several disks attached will have a disk
controller for timing, contention, data access, …
Input/Output (I/O) devices like disks and other
secondary memory devices (Jump drives,
etc.)are considered peripherals.
We won’t pay much attention to them.
For our purposes, the primary I/O devices will be the
keyboard and the monitor.
Output on a monitor is achieved by breaking the screen
picture into small pieces called picture elements (pixels).
The pixels are represented in the computer as numbers (as
is everything else) and each pixel has a specific ‘screen
A typical monitor can display a number of ‘screen
resolutions’ such as 640x480, 800x720, 1280 x 1024
These numbers represent the number of pixels used to
display the screen information.
Main Memory and Secondary
Main memory is made up of a series of consecutive
memory locations called addresses.
Associated with each memory location is a unique address.
On many computers, each memory location consists of 8
bits, or one byte of information.
The storage capacity of a device such as main
memory is the total number of bytes it can hold.
A kilobyte (KB) is 1,024 bytes or 210 bytes.
Larger units are a megabyte (MB), a gigabyte (GB), and a
It is usually easier to think about these capacities by
rounding them off.
Characteristics of Main Memory
When data is stored in a main memory
location, it overwrites (thus destroying) any
information that was previously stored there.
Main memory is said to be volatile.
The information stored in it will be lost if its power
is lost. (meaning of volatile in this context)
You should frequently save your work onto a
secondary memory device (such as a disk).
Secondary Memory Devices
A disk is a direct access (also called random access) device
since the read/write head moves quickly to the information needed.
In the prerequisite to this course, you have seen pictures of disks and
how they operate.
Disk is both a direct access device and can be accessed sequentially
just like a tape unit.
A tape must be sequentially processed / rewound / or fast-
forwarded to get to the desired information.
A tape is thus a considered a sequential access device.
While tapes were the medium of choice when disks were expensive and
access was controlled to those types of applications really needing
disks, tapes now are almost exclusively used for backup storage.
Very inexpensive and can store huge quantities of data – often
Two More Terms
Random Access Memory (RAM)
The terms RAM and main memory are basically
interchangeable. Sometimes called primary memory.
RAM should probably be called read-write memory since
data can be both written to it and read from it.
Read-Only Memory (ROM)
After information is stored on ROM, it cannot be altered
(easily). Data in ROM is ‘burned’ into the chips
Can sometimes be reprogrammed (PROMs) and sometimes
we have Erasable Programmable Read Only Memories
(EPROMs) (Need special equipment)
ROM chips are often embedded into the main circuit board
to provide the preliminary instructions when the computer is
initially turned on.
Other Memory Devices
Additional memory devices include CD-ROM, CD-
Recordable (CD-R) drives, CD Rewritable (CD-
RW) discs, DVD devices, jump drives, ….
(Know the differences)
The speed of a CD drive is expressed in multiples of X,
which represents a data transfer speed of 153,600
bytes per second.
Due to improvements in technology, storage
capacity approximately doubles every 18 months.
Central Processing Unit
The ‘processor’ interprets and executes your
program’s instructions one at a time – sequentially.
Consists of the arithmetic and logic unit, the control
unit, and the registers (usually in the ALU and Control
Registers store bits (16-bit registers; 32-bit registers, …)
Control Unit dissects the instruction and directs the
ALU to perform the calculations / comparisons using
CPU has other registers too:
Instruction register; program counter, more
CPU - more
The notion of a stored-program computer – a
von Neumann machine – stored both program
instructions and data together in main memory.
Fetch instruction from primary memory (RAM)
Decode instruction (to see what it is to be done)
Execute the instruction using registers
CPU - more
CPU on a chip called a microprocessor
Circuit board also contains communications sockets,
etc. for connection with video displays, etc.
Main circuit board also contains the system clock
Instructions are in synch with these pulses
Some take a single pulse; others, more.
Often called clock speed.
All activities in a computer and controlled by the clock
with something we call ‘clock cycles.’
We may say that an instruction executes in two clock cycles.
A network is two or more computers connected
together to exchange information.
Each computer of a network has a network address.
One technique to improve network speed is to divide
large messages into segments, called packets.
Packets have fixed formats and other constraints…
Then send the individual packets across the network
intermixed with pieces of other messages sent by other users.
Local Area Networks and
Wide Area Networks
A Local-Area Network (LAN) is designed to span
short distances and connect a relatively small
number of computers.
Within a building or small area
You may connect to the LAN here in this classroom and see
these slides/ take notes on them, etc.
A Wide-Area Network (WAN) connects two or more
LANs, often across long distances.
LANs connected by a WAN are often owned by different
companies or organizations, and might be located in
Generally, one computer takes care of communications.
The Internet is a network of networks.
Grew out of U.S Government ARPA (and ARPAnet)
In 2000, number of computers connected to Internet = 10 million.
A protocol is a set of rules that governs how two things
The software that controls the movement of messages across the
Internet must conform to a set of protocols called TCP/IP for
Transmission Control Protocol/Internet Protocol.
IP defines how information is formatted and transferred
TCP software handles the transmission and reconstituting of
messages, error control, etc. (contention, …)
Have layers of communications and different protocols…
Every computer connected to the Internet has an IP address
that uniquely identifies it among all other computers on the
IP Address vs Internet Address
An IP address is of the form 184.108.40.206.
Fortunately, Internet allows each computer to be given a
unique name - often referred to as its Internet Address.
The first part of an Internet Address is the local name of a specific
The rest of the name is the domain name.
Ours is: osprey.unf.edu.
Osprey is local name
unf.edu is the domain name.
Can have ‘subdomains’ within domain for departments, etc.
Last part of domain name is the ‘top level domain name’.
Some are: .edu .com, .org, .mil …
The Domain Name System
The Internet uses another software program,
the Domain Name System (DNS) to translate
an Internet Name (osprey.unf.edu) to a
corresponding IP Address (220.127.116.11).
Each organization connected to the Internet
operates a domain server that maintains a list of all
its computers and their IP addresses.
Used for mapping.
The World Wide Web
The World Wide Web (also known as WWW or the
Web) makes the exchange of information easy.
Web software provides a common interface through which
many different types of information can be accessed with a
Web: based on concepts of hypertext & hypermedia.
Hypertext – based on links to support jumping as needed. To
manage large amounts of information. Basically used to originally
Hypermedia incorporates graphics, sound, animations, and video.
Hypertext and Browsers
Web Server: computer dedicated to
providing access to Web documents.
Web documents are written in a variety of
languages now. Originally, there was just
html. Now there are many with many
Browsers load / interpret documents provided
by a Web server.
Many documents are formatted using the
HyperText Markup Language (HTML).
Links to Java programs can be embedded in html
documents and executed through Web browsers. 28/73
Uniform Resource Locators
Information on the Web is found by identifying a Uniform
Resource Locator (URL)
A URL uniquely specifies documents and other information for a
browser to obtain and display.
An example URL is http://www.unf.edu
We sometimes now just say, web address…
First piece of URL is the protocol (HyperText Transfer Protocol –
HTTP in this example) which determines the way the browser
The second piece is the Internet address of the machine on which
the document is stored.
A typical third piece of information is the file name of the file you
wish to view.
Default third piece: index.html 29/73
Another Sample URL
In this URL, the protocol is http (HyperText Transfer Protocol).
Machine referenced is www (web server found at unf.edu)
Information is stored in a ‘file’ in my home directory named
Fall2009.html (programmed in html)
www.unf.edu/~broggio by itself, refers to an index.html file stored in a
directory, broggio, within some UNF web server
The Internet vs the World Wide Web
The Internet makes it possible to communicate via computers
around the world.
Internet IS a network; Communications…
The Web makes that communication a straightforward and
enjoyable activity via software.
The Web can be used on a LAN or even a single machine that is not connected to any
Information service based on a set of software applications
A global network connecting millions of computers.
Hundreds of countries are linked into exchanges of data,
news and opinions.
Unlike online services, which are centrally controlled, the
Internet is decentralized by design.
Each Internet computer, called a host, is independent. Its
operators can choose which Internet services to use and which
local services to make available to the global Internet community.
Remarkably, this anarchy by design works exceedingly well.
There are a variety of ways to access the Internet. Most
online services offer access to some Internet services.
Internet Service Providers (ISP): Comcast, AOL, etc.
The Internet is not synonymous with World Wide Web.
World Wide Web
A system of Internet servers that support specially
The documents are formatted in a markup language
called HTML (HyperText Markup Language) and a host
of other languages that support links to other documents,
as well as graphics, audio, and video files.
This means you can jump from one document to another
simply by clicking on hot spots. Not all Internet servers
are part of the World Wide Web.
There are several applications called Web browsers that
make it easy to access the World Wide Web; Four of the
most popular being Netscape Navigator, Microsoft's
Internet Explorer, Mozilla Firefox, Safari, and others.
World Wide Web is not synonymous with the Internet. 32/73
The rest of this course explores the process
of designing and developing programs using
an object-oriented language. Ours is Java.
All of the software we have discussed including
the Internet and Web protocols are simply (but not
simple) programs some programmer has written.
Next section discusses the purpose of
programming in general and introduces the
Java Programming Language.