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COMPUTER LIFE IS PROBLEM |
06.07 |
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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.
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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
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+ 0x2
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4 + 0x2 3 + 0x2
Description: Could not connect to the server "127.0.0.1".
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:.
BIT
Units
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Equivalent
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Milliseconds
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1/1000 seconds Microsecond
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1/1000000 seconds
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Ns
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1/1000000000 seconds Pikodetik
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1/1000000000000 seconds 3. Frequency Units
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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
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ie greater Kilohertz and megahertz. 1 Kilohertz (KHz) = 1000 Hertz (Hz) and 1 megahertz (MHz) = 1000 Kilohertz
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1. COMPUTER SYSTEM It is known that the computer is part of the information system and is
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hardware. As a system, the computer consists of several components.
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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)
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• Device output (output device)
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• 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
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buses, namely:
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• 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
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output.
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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
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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).
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At present, the CPU is a component of size mikroprosessor relatively small. Mikroprosessor itself is a computer on a chip.
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Chip is a piece of semiconductor material that contains a number of components.
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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.
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