COMPUTER

CHAPTER I
HARDWARE
Before discussing the technical aspects of computer systems we need to understand about
units that are specific and to facilitate the understanding of the unit -
units used, the various units that need to know will be discussed first
first.
1. Bit / Byte
Computer system works on the basis of binary numbers, called binary
is the number that had known only digits 1 or 0, and there are only two digits are
used. In the mathematical system of numbers is called integer-based 2.
Value 0 or 1 usually called bits (binary digits). In the computer system digit "0"
means "no" and the digits 1 states "there".
Any of a number can be expressed by a series of digits 0 and 1.
For example:
10000010
Is a binary number that contains 8 digits and is identical with the number 130
the common number system we use (called sistemdesimal or system
10-based numbers. To calculate the numbers above equivalence with
decimal decomposition can be done as follows:
10000010 = 1x2
7
+ 0x2
6
+ 0x2
5
+ 0x2
4
+ 0x2
3
+ 0x2
2
+ 1x2
1
+ 0x2
0
= 130.
2. Units Left
The speed of computers in processing an instruction is very high. Order
time spent working on an instruction far below 1 second.
Therefore it is important to know the various units of time such as tables
follows:.
Units
Equivalent
Milliseconds
1/1000 seconds
Microsecond
1/1000000 seconds
Ns
1/1000000000 seconds
Pikodetik
1/1000000000000 seconds
3. Frequency Units
Frequency measured in hertz. Frequency means the number of cycles in one second. 1
Hertz in one second means is formed of a cycle. Size frequency
ie greater Kilohertz and megahertz. 1 Kilohertz (KHz) = 1000 Hertz (Hz)
and 1 megahertz (MHz) = 1000 Kilohertz
1. COMPUTER SYSTEM
It is known that the computer is part of the information system and is
hardware. As a system, the computer consists of several components.
Generally, the components in a microcomputers (PCs) are divided into:
• central processing unit or also known as CPU (Central Processing Unit) Page 2

• Main memory (main memory)
• Device input (input device)
• Device output (output device)
• secondary storage tool
Relationships between components in the computer system shown in the following figure:
Bus
Buses can be thought of as a path or channel. The bus serves as a place
passing data from one component to another component. There are 3 types of trajectories
buses, namely:
• data bus functions to pass data to and from main memory.
• Bus address used to send the signal that states address
in the main memory.
• Bus control function for sending a state signal data
read or written to and from main memory, input devices or devices
output.
The bus has a characteristic called the bus width (number of bits that can be dilintaskan
at a time) and bus speed (speed of data states that can
distributed in the bus). Bus width is measured in bits and speed of the bus
expressed in units of MHz. Page 3

A. CPU
CPU (central processing unit) or processor is often described as the brain
computer. Penganalogian like this are not entirely correct, because one
brain function that is given is not a part of the CPU (but handled by the
component called a memory).
At present, the CPU is a component of size mikroprosessor
relatively small. Mikroprosessor itself is a computer on a chip.
Chip is a piece of semiconductor material that contains a number of components.
CPU contains two important parts are:
1. Control Unit (Control Unit)
Serves to control all components in a computer system, such as the brain
man who controls all the nerves in the body so that all members
body can be driven or controlled.
2. Arithmetic and Logic Unit
Role in carrying out the calculation operations (arithmetic) as
subtraction, multiplication and addition operations and benchmarking (logic)
like comparing a value of zero or not.
ALU has a component called a register. This component of memory
special high-speed dipakaim to store the results
sementera ALU operations and to store certain control information.
Mutiprosesor
In some computer systems the number of processors that can support more than one. In
currently a PC can contain 2 to 4 processors. While
workstation can have 20 processors, even the IBM supercomputer that is used
the United States Department of Energy has 8192 processors working in
tandem and can perform 10 trillion calculations per second (Turban, McLean and
Wetherbe, 1999).
Multiprocessor systems are often divided into:
• SMP (Symmetric Multiprocessor)
Is a multiprocessor system with each processor working in
its own (not mutually dependent). In this system a CPU can be
are dealing with a process, for example, are processing and spreadsheets
CPU is doing the graphics.
• Vector processors
Stating a multiprocessor system with each processor can
working in unison in dealing with vector calculation process.
• Parallel Processor
Stating that the system has a number of processors and has a characteristic
as follows:
1. There was no processor which acts as the main processor
2. Some processors do not always do the same operation in time
same.
By using a parallel processor, the parts of a program can
done by the processors differ. Handling processor Page 4

the process is handled by the program. This type of processor used in
super computers.
• massive parallel processors (massively parallel processor or MPP)
• It is a system that contains hundreds or even thousands of processors that can
penedekatan interact with neural networks. This processor is
applied in business. One user is Wal-Mart
(Laudon, 1998).
Next image differences parallel processors and massive parallel processors.
B. Main Memory
Main memory (main memory) is often called the primary memory (Primary memory) and
internal memory (internal memory). This component serves as a reminder. Deep
this case, the memory can be stored in the form of data or programs. More
detail, the main memory serves to:
• Save data from input devices to the data sent to the ALU
to be processed.
• Storing data ALU processing before being sent to the output device.
• accommodate the program / instruction from the input device or devices
secondary reminder.
Common memory divided into 2 types namely:
1. RAM (Random Access Memory) is a type of memory whose contents can be replaced -
change during the computer is turned on and can remember the character of data or
there is the program for the electric current (computer starts). Also RAM can
store and retrieve data very quickly.
2. ROM (Read-Only Memory) is a type of memory that can only be read.
Provided by computer vendors and contain programs or data. Page 5

Chache Memory
Is a memory that has a very high speed which is used as an intermediary
between RAM and CPU. This memory has a higher speed than the RAM,
but with a more expensive price. This memory is used for menjebatani
CPU speed difference is very high with the RAM speed is much more
low. By using the cache, some data can be transferred to this memory
at a time, and then ALU will retrieve the data from this memory.
With this approach, pemrosesn data can be performed more quickly than
if the CPU takes the data directly into RAM.
CPU
Chache
Memory
Memory
Main
Cache memory as the interface between main memory and CPU
C. Input Device
Input device (input device) is any equipment that can be used to
enter data into the computer. Data is entered here in the form
text, images, sound and video. At this time belonging to the input device is
many, from keyboards to voice recognition.
Various input devices:
1. Device typing:
- Readers plomg card (punched card reader)
- Keyboard
2. Pointer devices
- Mouse
- Touch screen
- Pena luminous (light pen)
- Joystick
- Stylus
3. Handwriting recognition
4. Voice recognition
5. Identification made optically
- Bar code scanner
- Wand reader
- Optical scanner
6. Other devices
- Digitizer.
- Glove, headset, and walkers Page 6

- Camera
- Smart card (smart card)
- Magnetic Card
- Readers retina
- Fingerprint reader
D. Output Device
Output device (output device) is the equipment used to provide
results of computer processing.
Monitor
Monitor is a common output devices used. In principle, the monitor
is a video screen or often referred to as VDU (Video Display Unit).
The technology commonly used in a CRT monitor (cathod ray tube) which
using electronic tube. Pixels on the display screen is formed because the surface
fluorescent due to the electron gun shots. The new technology allows CRT
disabled so that the size of the monitor is much thinner and present the screen
flat. This monitor is made by using LCD (Liquid Crystal Display).
This technique is also applied to a laptop or notebook screen.
Printer
Printer is a device that functions to print computer output (in
hardcopy form). Printer can be divided into:
1. Impact printer
Is the type of printer that works like a conventional typewriter. Prints
obtained in the paper because there is a blow to the media (carbon or ribbon)
to the paper. Included in this category, namely:
• Dot matrix (a printer that uses a set of print heads
needle)
• Daisy wheel (wheel printer that uses that contains the character -
characters)
• Line printer (the printer that prints one line per time).
Typical impact printer:
• Slow
• Noisy
• Quality prints of pictures (even if it can) is not good.
2. Nonimpact printer
Printer is not working with a punch. Included in this category
This is a laser printer, thermal printers and ink-jet printer.
Laser printer is a printer that works on the basis of a laser beam. Result
High quality, both for text and images.
Thermal printer is a printer that works on the basis of specific heat in the paper
is sensitive to heat. Page 7

Ink-jet printer, or sometimes called Buble-jet printer is a printer
work on the basis of ink spray in the size of the dots is very small to
paper.
Plotter
This equipment is equipped with a number of colored pens that can be used to
create high-quality images. For example to create charts or graphs. Many
used for engineering and architectural applications.
Voice Output
To provide a sound output devices are generally required of speakers.
In this case the speaker can be used internal or external speakers.
Used the internal speakers on your PC while connected to external speakers
PC through the sound card (sound card)
Output in the form of a regular voice is presented in multimedia applications.
E. Secondary Reminder Device
These devices consist of all equipment that can be used to store data
permanently and sometimes can be read back.
1. Ribbon Magnetic (manetic tape)
Is a reminder of secondary devices commonly used for the purposes of
backups (backups). Realization can be a big roll of tape in (reel
tape), Catridge (such as video tape) or cassettes.
The weakness of the magnetic tape is in how pengaksesannya.
By accessing the sequential approach (in order), reading the data on
any position in the band has to start from scratch. This situation
make reading data on magnetic tape to be slow.
2. Magnetic disc (Manetic Disk)
Secondary reminder is commonly used in computers. Disc
magnetic using direct access method, without the need
read the data so lain.Dengan data readings can be done
quickly.
Magnetic disc can be divided into:
• Hard disk
Secondary reminder is intended to be installed in
settled on the computer and not to meant to be carried.
• Floppy disk (floppy disk)
Created with the aim that the data can be transferred from one computer
to another computer. By its very nature as a regular disk called
removable disk.
3. Optical disc (Optical Disk)
Is a disc that can hold hundreds of times the data than
diskette. So-called compact disk (CD) or a laser optical disk)
There are a variety of optic disc are:
• CD-ROM (compact disk read-only memory) Page 8

Is the type of optical disc which has the properties can only be read.
Usually made by the vendor to make way for mass production
accommodate books, encyclopedias, multimedia materials or programs. As
example, CD-ROM 4.72-inch size can accommodate 680 MB
data.
• WORM (write once read many)
Can be written by a computer, according to the recording name only
can be done once. After recording the contents can not be changed. CD
This is useful for storing documents, design drawings, songs and other -
Another intended as a backup.
• CD-Rewitable
Allows existing data on the disc removed and replaced
with new data. Working principle of this CD as follows:
1. Using a laser to heat the recording surface delete
2. Using a combination of laser and technology to write megnetik
to the surface of the recording.
3. Read data through a laser beam.
• DVD (digital video disk or digital versatile disk)
Is the latest technology in optic disc. Generally DVD
already in circulation are DVDs that can only be read (DVD-ROM) and
used to store movies theaters. But the actual DVD
a
can ditulisipun existing .. In 1887, Hitachi
announced the first DVD that can be inscribed with a capacity of 5.2
gigabyte. Here are the different types of DVDs that are available in the market:
DVD-R: This type of DVD that can only be written once, Capacity 4.7
GB
DVD-RW, DVD-RAM, DVD + RW: This type of writable DVD
many times.
DVD-ROM: This type of DVD that can only be read.
2. COMPUTER EVOLUTION
Computer marked by the birth of the modern electronic computer called
ENIAC (Electronic Numerical Integrator and Computer). This computer was created in
the year 1946 at the University of Pensylvania, United States, by Dr.. John W. Mauchly and
J. Presper Eckert, Jr.. Originally intended to perform ballistic calculations.
However, when completed, ENIAC is a versatile machine. Until
now that computers have created is divided into 5 generations.
The following table of characteristics of various generations of computers.
Generation
Components
Main Memory
Cycle time
First
Vacuum
2 K
100 milliseconds
Both
Transistor
64 KB
10 microseconds
Third
IC
4 MB
500 nanoseconds
Fourth
LSI and VLSI
16 MB
800 pikodetik
Fifth
VLSI
64 MB
2000 pikodetik Page 9

1. First Generation Computers
The first generation of personal computers between 1946 to 1956.
The characteristics of the first generation of computer:
Using a vacuum tube (vacuum-tube) as the main component for
store and process information, so the size of the computer becomes
greater.
Memory needed in the form of delay line, elektrostattik tubes, drums
magnetic.
Examples include computer that this generation is: ENIAC, CADAC 100
Series, datamatic 1000, EDVAC, 701,702,650,704,705 and 709 IBM, UNIVAC I and
II, SEAC, SWAC, RCA Bizmac, Datatron 203.204 and 205, Harvad Mark III and IV.
2. Second Generation Computers
Period of the second generation of computers ranged from 1957 to 1963
The characteristics of second generation of computers:
Wearing sized transistors are relatively much smaller
More reliable
Cheaper and not as hot as vacuum tube
All second-generation computer memory using a magnetic core.
Used for business and scientific applications
Examples of second generation computers are: CDC 1604.3600, atlas Ferranti, Honeywell
800, IBM 7000 and IBM Series 1400 series, 2000 Philco, RCA and UNIVAC 302.501
III, 1107.
3. Third Generation Computers
Third-generation era ranged from 1964 to 1979
The characteristics of third generation computers:
Using components of IC (Integrated Circuit). An IC contains
hundreds to thousands of transistors, but it also contains a resistor and
diode.
Has a size relatively small and have the ability to
much improved than the second generation
Examples include computer that this generation is: Amdahl 470 VC / 6 system,
Burroughs B5500, B6700, 1700, CDC 6000, Cyber 70 series, DEC's PDP-10, 11, GE
400.600, IBM S/360, S/370, System 3, 1108,1110,9400 UNIVAC.
4. Fourth Generation Computers
Beginning in 1980 and lasted until now.
The characteristics of fourth generation computer:
LSI technology (large scale integration) and VLSI (very large
scale integrated). VLSI technology allows a single chip
small size may contain hundreds of thousands of transistors and components
other electronics.
Which includes this generation is the IBM PC, IBM AS/400, Fujitsu DS/90 Page 10

5. Fifth Generation Computer
Unlike the four previous generation architecture based on
Von Neumann, a fifth-generation computer using the massively parallel processor
(MPP). With this approach, low-cost computers can be made to
rival supercomputer speed.
RAGAM COMPUTER
Classification of computers and their uses:
1. Supercomputer
The systems have the greatest speed the process, often used
to handle applications involving the most complex calculations,
for example for weather forecasting and design of the rocket. Supercomputer
famous Cray (Cray Research, Inc.).
2. Mainframe
The systems are used in large-scale companies
large to handle data processing with a very large volume.
3. Minikomputer
Often called a midrange system, usually used in companies
medium scale as a server.
4. Workstation
The term is often confusing workstation. On systems that use
Novell Netware, PC workstations located means as a client,
But understanding the type of computer workstations is not like
sense. Workstation is a type of computer that is more potent than
most PCs.
5. Microcomputer
Better known as PC (Personal Computer) or a personal computer.
Microcomputer itself can be divided into:
Desktop is the kind of large-sized microcomputers, the general
used in the home or office.
Laptops are easy to type microcomputers to carry
travel.
Notebook (mini laptop) has properties such as laptops. Only
size slightly smaller than a laptop. Physically, laptops and
notebook is often difficult to distinguish.
Palmtop or can be called hendhelp PC (handheld PC) is
computer slightly larger than a calculator that can
placed above the hand.
PDA (Personal Digital Assistant) is a type of handheld computer
using a pen instead of a keyboard. Some PDAs also have
equipped with a mini keyboard that can be folded. Page 11

CHAPTER II
SOFTWARE
A. Grouping Software
Computer will be useless without the existence of software (the software). Computer
work on the basis of instruction. A set of instructions is known as the program
or a computer program.
The software can be classified as follows:
1. Program System (often called the software support or support
software) is a program used to control the resources
computers, devices such as CPU and input / output. This program is as
intermediary between application programs and computer hardware.
Program the system can be divided into 3:
The program is a system controller that controls the program
the use of hardware, software and data on the computer
during the program run. For example the operating system.
System support program is a program that supports
operation, management, and user of computer systems by providing
a variety of services. Included in this program group is
utility, monitors system performance and security monitoring.
The program is a system development program aimed at
assist users in making / developing the program. Including
in this category is the compiler and interpreter.
2. Program Application (often simply called an application only) is a program that
made by the user intended to perform a specific task.
The program is divided into 2, namely:
Versatile application programs are application programs that can
used by the user to execute the things that are common
(eg to create a document or to send a letter of
electronically) and to automate the individual tasks that
are repeated (for example, to perform calculations
which is routine) included in this category include the DBMS
simple, Web browsers, electronic mail, word processors (word
processor), spreadsheets (spreadsheets) and presentation programs. Programs
versatile applications often called end-user software (end-user
software).
Specific application program is a program aimed at
handle things very specific. For example, programs on the system
POS (point-of sale) and ATM. Included in this category is
program called the application package or software package.
Example Deac Easy Accounting (DEA) is used to handle
accounting problems. Page 12

B. VARIOUS SOFTWARE
1. Spreadsheet
Is a versatile program for managing data in tabular form and can be
perform calculations on the data dynamically.
2. Word Processor (word processing)
Is the common name for the program used to make documents.
3. Program Presentation
Is a program used to create presentation materials and at the same time
for presentations. Examples of Power Point presentation program environment
StarOffice Impress windows and Linux environments.
4. Image Processing
Image-processing program (image processing) is a program used to
manipulate images (pictures or photographs). Examples of this program is Adobe
Photoshop windows environment, and GIMP in Linux environment.
5. Electronic Letters
Communication programs provide a means for communication between
users electronically. The most commonly used is the program
used to receive or send electronic mail (e-mail).
6. Groupware
Groupware is software that is used to perform
collaboration, which helps some people to handle the job
group. This software supports collaboration tools like mail
electronic, databases, discussion groups, scheduling and others. Example groupware
including: Lotus Notes, Novell Groupwise, Exchange and Netscape Microft
Communicator.
7. DBMS
Program is intended to implement data management. Device
This software provides the facility to store data, manipulate data and
retrieve data in a way that is easy and fast. Example Microsoft Access
environmental windows and MySQL Linux environments.
8. Personal Information Manager
Personal Information Manager (PIM) is a program that is very
beneficial for individuals who want to manage personal information. Device
This software provides facilities such as store and organize
customer or client information and to record the meeting schedule.
Example Lotus Organizer and Microsoft Outlook.
9. Web Browsers
Is a useful software to access the web information or
to conduct transactions via the web. Microsoft Internet Explorer and Netscape
Navigator is a famous example of browser windows environment.
10. Software Suite and Integrated Package.
Software Suite is a collection of collection of several programs that are packed
become one. Some well-known is Microsoft Office, Lotus SmartSuite
and StarOffice. Page 13

C. MULTIMEDIA SOFTWARE
With increasingly widespread use of multimedia for various purposes,
multimedia software industry also grew rapidly. As
known, multimedia is a technology that combines the ability
text, images, sound, animation and video images.
Some software-related multimedia such as:
Adobe premiere: The software used to make films
in various formats such as Microsoft AVI (*. AVI) and QuickTime
(*. MOV)
Winamp: Software to play the various types of audio files,
as MP3
Jet-Audio: The software can be used to convert sound
in the cassette or VCR into digital data.
Macromedia Shockwave: Software to create web pages
equipped with audio and animation
D. OPERATING SYSTEM
The operating system is a program that acts as an intermediary between the user
computers and computer hardware.
The purpose is to provide the operating system environment that enables users
can run any program easily.
Main Function Operating System:
1. Management process includes the preparation, scheduling and monitoring process
on the computer. The process is running programs.
2. Resource management related to control over the use of
resources in computer systems by both system programs
computer programs. The meaning here is the resource component
in computer hardware such as CPU, main memory, and devices
input / output.
3. A data management control over the data input / output, including
in regard to the allocation of secondary storage devices as well as in
main memory.
In connection with the handling process conducted by a number of known users
with terms such as:
1. Multiprogramming
Is a method that allows two or more programs executed
simultaneously within a computer, sharing of resources within the
different. For example, at one time a program is using
CPU, while other programs use the printer. In the system
multiprogramming, a program executed in the CPU until there is an interruption,
as demand input. At the time the program asking for input, the next program Page 14

which has been loaded in the memory will run until there is an interruption. When
interrupt processing has ended, control is returned to the dienterupsi program.
Such as repeated cycles so that the programs have been loaded the main memory
processed.
Weakness multi-programming system is not allowing users to interact
with the process. Any input is handled by the control card, known as
plong card title.
2. Time-Sharing
Is a method used by the operating system that allows several users
can run several programs at the same time. General way
PC system. By using the windows operating system, someone can
run the program Word to create documents and sekaliguis run
excel program to make calculations in the table. Users can
move from one program to another program with ease and every program remains
executed by the CPU.
3. Multiprocessing
Is an operating system's ability to run two or more instructions were
simultaneously by using a number of CPUs in a komputer.Dengan
Such an approach, the operating system can set the number of CPUs running
the instructions differently located in a program within the
same.
E. UTILITY
Bantu is a useful program to perform activities related
with system resources, such as to make the data on the hard disk defragmentation.
Environmental windows programs such as Scandisk, disk cleanup and disk
Defragmenter, which belong to the system tools, is an example of utility.
F. PROGRAMMING LANGUAGE
It is known that the program is a set of instructions used to
set the computer hardware to perform certain actions. Activities
related to the writing program called the programming.
Characteristics of programming language depends on the purpose, for example, programs
intended for batch processing are different from the intended program
for real-time processing.
Programming language evolution
The languages that are used to set the hardware has undergone evolution
several times. So far known as the 5th generation programming language.
Peratama generation programming language
Using a machine language to express instructions for the computer. Of
it is very difficult language understood by a layman and very boring
for the programmer, other than that each machine has its own code. Page 15

Second-generation programming language
Using assembly language instead of binary codes, is used
short words, such as MOV to say "Move" and JNZ
which means "non-zero jump" or "jump if not equal to zero".
The language is a bit easier to understand than machine language for remembering
command in the words dipendekan easier than recall
rows of binary numbers.
Third-generation programming language
Third-generation programming language using the procedural approach.
As a programming language to write the instructions detailed in order
computers do their job. Programs written using the words
used the word human, as WRITE to show something to
READ the screen and to read data from the keyboard.
But given the actual computer code known only in the form of
binary, programs written by programmers who need to be translated into the language
machines using software called a language translator
(language translator). This translator program that changed the program
high beraras (the so-called source code or source code) into the
machine code (which is called object code or object code).
Translator can be divided into:
1. Compiler
Is a translator program that converts all the source code
object code. Results of this object code that can be run by
computer. Please remember to do the translation process used
called compilation.
2. Interpreter
Is a program that translates a single instruction in the source code
and then immediately run the instructions are translated.
Fourth-generation programming language
This programming language is designed to reduce programming time in
create a program that is expected to increase programming productivity and
programs can be made in a shorter time. Programming language
fourth generation commonly called 4GL can be used by the user
yang kurang mengetahui hal-hal teknis tentang pemrograman tanpa bantuan
pemrograman professional.
Bahasa generasi keempat mendukung :
Pembangkit program (application/program generator)
Pembangkitan laporan (report generator)
Bahasa query (biasanya menggunakan SQL), dan
Pembangkitan gambar (graphics generator).
Contoh bahasa generasi keempat :
- Oracle
- Informix
- Sybase Page 16

- PowerHouse
- Access
Bahasa pemrograman generasi kelima
Merupakan kelompok bahasa pemrograman yang ditujukan untuk menangani
kecerdasan buatan (artificial intelligence). Kecerdasan buatan adalah disiplin ilmu
komputer yang mempelajari cara komputer meniru kecerdasan manusia. Various
aplikasi kecerdasan manusia adalah seperti berikut :
Pemrosesan bahasa alami (natural language processing) yakni mengatur
komputer agar bisa berkomunikasi dengan manusia melalui bahasa
manusia (inggris,spanyol,perancis,indonesi dan sebagainya).
Pengendalian robotika dengan sensor mata
Aplikasi sistem pakar (expert system) yang meniru seorang pakar dibidang
tertentu sehingga bisa menghasilkan nasihat atau pemikiran yang setara
dengan seorang pakar.
Kecenderungan Pemrograman Masa Sekarang
Model pemrograman terus berkembang, sehingga kecenderungan bahasa pemrograman
sekarang adalah :
1. Pemrograman Terstruktur
Pada bahasa pemrograman generasi ketiga pemrograman terstruktur mulai
introduced. Secara teori instruksi semacam GOTO mulai dihilangkan dan
sebagai penggantinya digunakan struktur control program.
2. Pemrograman Berorientasi Objek
Pemrograman berorientasi objek (Object Oriented Programming atau OOP)
adalah mengkombinasi data dan prosedur-prosedur untuk mengakses data dan
prosedur-prosedur untuk mengakses data menjadi sebuah kesatuan unit. Unit
dikenal dengan nama objek (object). Objek sebenarnya mencerminkan pola kerja
manusia dalam kehidupan sehari-hari. Sebuah objek diibaratkan sebagai
departemen-departemen di dalam sebuah perusahaan bisnis, misalnya departemen
pemasaran,akuntansi maupun personalia.
Pemrograman berorientasi objek memiliki tiga karakteristik utama
Pengkapsulan
Merupakan pengemasan data dan prosedur dalam objek. Pengkapsulan
merupakan penyembunyian informasi (information hiding) yang
diterapkan pada pemrograman terstruktur sehingga data tidak dapat
diakses secara langsung oleh pihak luar objek.
Pewarisan
Merupakan sifat dalam bahasa berorientasi objek yang memungkinkan
sifat-sifat dari suatu kelas diturunkan ke kelas lain.
Polimorfisme
Merupakan suatu konsep yang menyatakan sesuatu nama yang sama dapat
memiliki berbagai bentuk dan prilaku yang berbeda. Page 17

3. Pemrograman Visual
Pemrograman visual menggunakan konsep yang disebut pemrograman
berorientasi objek dan pemrograman yang dikendalikan oleh kejadian. (even
driven). Oleh karena pemrograman visual menggunakan pemrograman
berorientasi objek, komponen-komponen yang menyusun antarmuka berupa
sejumlah objek. Setiap objek memiliki properti atau data , kejadian dan metode
certain.
Properti adalah segala atribut yang menyangkut objek. Misalnya formulir
memiliki property yang berkaitan dengan judul formulir (misalnya pada
Visual dBase disebut text). Artinya melalui property ini judul formulir
dapat diubah.
Kejadian menyatakan berbagai aktivitas yang akan dipantau oleh program
dan aktivitas ini telah didefinisikan oleh sistem. Misalnya terdapat
kejadian klik pada tombol perintah. Dengan memberikan kode terhadap
kejadian ini, maka kode ini akan dijalankan kalau pemakai mengklik
tombol.
Metode adalah suatu fungsi atau prosedur yang melekat pada objek.
G. PERANGKAT LUNAK MENURUT BIAYA
Berkaitan dengan biaya untuk mendapatkannya perangkat lunak dapat dikelompokan
menjadi :
1. Perangkat lunak komersial
2. Shareware
3. Freeware
Perangkat lunak komersial :
Adalah perangkat lunak yang harus dibeli kalau pemakai bermaksud menggunakannya.
Perangkat lunak seperti Microsoft Office merupakan contoh perangkat lunak komersial.
Shareware
Adalah perangkat lunak yang bisa digunakan oleh pemakai dengan tujuan untuk
dievaluasi selama masa tertentu tanpa membayar sama sekali dan jika sesudah masa
tersebut berlalu pemakai bermaksud tetap menggunakannya maka ia perlu membayar ke
pembuat pembuat perangkat lunak tersebut.
Freeware
Adalah perangkat lunak yang dapat dipakai oleh siapapun tanpa perlu membayar sama
once.
Open Source Software
Sebelum open source digunakan, perangkat lunak yang tersedia dalam bentuk biner
maupun kode sumber biasa disebut free software. Menurut Stallman (1999), sebuah
program dikatakan sebagai free software bagi pemakai jika: Page 18

Pemakai memiliki kebebasan untuk menjalankan program tersebut untuk tujuan apa
only.
Pemakai memiliki kebebasan untuk mengubah program sesuai dengan
needs.
Pemakai memiliki kebebasan untuk mendistribusikan kembali salinannya, baik
secara gratis atau dengan biaya.
Pemakai memiliki kebebasan untuk mendistribusikan versi hasil modifikasi dari
program sehingga komunitas dapat memperoleh manfaat dari pengembangan
pemakai.
Jadi pengertian “free” pada free software cenderung kearah kebebasan (freedom) dan
bukannya free dalam arti gratis. Stallman (1999) juga menjelaskan bahwa free software
dan open source sebenarnya menyatakan keadaan yang sama terhadap perangkat lunak,
tetapi memiliki perbedaan pandangan. Dapat dikatakan bahwa open source menekankan
pada kehandalan dan fleksibilitas dalam mengembangkan program, sedangkan free
software. Menekankan pada kebebasan dari pengontrolan oleh pihak lain.
Definition
Official
about
open
source
tercantum
pada
site
http://www.opensource.org/osd.html . Secara prinsip open source memperkenankan siapa
saja untuk mendistribusikan perangkat lunak yang tergolong sebagai open source secara
gratis atau dengan bayaran dan tak ada royalty atau kompensasi yang perlu diberikan.
Prinsip penting lainnya adalah bahwa sekiranya terdapat orang yang mengubah kode
sumber,referensi terhadap pencipta asalnya tetap perlu dituliskan, sebagai bentuk
penghargaan.
Untuk memperoleh informasi lebih lanjut tentang shareware,freeware dan open souce
atau untuk mendapatkan perangkat lunak itu silahkan mengunjungi situs-situs berikut :
http://www.shareware.com/
http://www.simtel.net/
http://www.intrastar.net/
http://www.bestdowmload.com/
http://www.opensource.org/
http://www.free-soft.org/
http://www.asp-shareware.conm/
TUGAS KE -2 :
Buatlah artikel tentang perkembangan salah satu perangkat keras dan perangkat lunak
yang anda ketahui.
Tugas dikumpulkan paling lambat 15 mei 2007.