Gerhana Matahari akan muncul di Indonesia

Akhirnya, setelah sekian lama, Gerhana matahari akan segera menyapa Indonesia. Tidak tanggung-tanggung, 3 gerhana matahari secara berturut-turut akan melewati Indonesia dalam rentang waktu 2009 - 2010. Sayangnya, tidak semua bagian di wilayah Indonesia dapat melihat fenomena ini. Karena, ketiga gerhana ini cuman melewati bagian barat dan/atau utara indonesia.Tahun 2009 tercatat ada dua gerhana yang akan melewati Indonesia, yaitu pada tanggal 26 Januari dan 21-22 Juli, sementara itu, gerhana matahari akan kembali menyenggol kita pada tanggal 15 Januari 2010. Fenomena ini sangat disayangkan untuk dilewatkan, karena gerhana matahari baru akan menyapa kita kembali pada tahun 2016.

1. Gerhana 26 Januari 2009
Yang paling spesial dari ketiganya adalah Gerhana pada tanggal 26 Januari yang jatuh pas di hari libur Imlek. Gerhana ini dapat dilihat oleh hampir seluruh masyarakat Indonesia (Dari Banda Aceh sampai Ambon), beruntunglah mereka yang tinggal di daerah Lampung, Samarinda, dan Teluk betung, karena bulan menutup hampir seluruh bagian matahari. Gerhana ini terjadi pada waktu sore hari sekitaran pukul 3 - 4.
Yang perlu diperhatikan dari jenis gerhana ini adalah jenis gerhana ini adalah gerhana matahari anular (bukan total) artinya ukuran bulan tidak cukup besar untuk menutupi seluruh priringan matahari berbeda dengan gerhana matahari total dimana bulan menutupi seluruh piringan matahari. Jadi, untuk melihatnya, perlu digunakan lensa pelindung mata, serta bagi fotografer, ingat untuk melindungi lensa kameranya sebelum mengabadikan fenomena langka ini.

2. Gerhana Matahari 22 Juli 2009
Gerhana ini cuma dapat dinikmati oleh mereka-mereka yang tinggal di bagian utara Indonesia seperti: Banda Aceh, Jayapura, Manado, Medan, Padang, Palu, Pekanburu, Pontianak, Samarinda, Sorong, Ternate.
Jenis Gerhana ini adalah gerhana Matahari Total, namun di Indonesia, bulan hanya akan menutup sebagian kecil dari matahari. Jika ingin melihat gerhana matahari total ini secara full, anda bisa ke Shanghai, karena disana, Bulan akan menutupi seluruh bagian matahari.

3. Gerhana Matahari 15 Januari 2010
Fenomena alam ini cuman bisa dinikmatin oleh mereka yang tinggal di bagian utara dan barat Indonesia seperti: Balikpapan, Banda Aceh, Tanjungkarang Telukbetung, Bandung, Banjarmasin, Bengkulu, Jakarta, Manado, Medan, Padang, Palembang, Palu, Pekanbaru, Pontianak, Samarinda, Semarang, Surakarta, Yogyakarta. Bagian Timur Indonesia sudah keburu malam ketika bayangan bulan melewati bagian sana. Sama halnya dengan gerhana Juli 2009, bulan cuma akan menutup sebagian matahari saja. Karena pusat jalur Gerhana Matahari ini melewati daerah India dan Cina sana, sehingga di Indonesia cuma kebagian sebagian kecil bayangan dari Bulan.

sumber : kaskus.us

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mysql_manual

MySQL is a database management system.

A database is a structured collection of data. It may be anything from a simple shopping list to a picture gallery or the vast amounts of information in a corporate network. To add, access, and process data stored in a computer database, you need a database management system such as MySQL. Since computers are very good at handling large amounts of data, database management plays a central role in computing, as stand-alone utilities, or as parts of other

applications.
MySQL is a relational database management system.

A relational database stores data in separate tables rather than putting all the data in one big storeroom. This adds speed and exibility. The tables are linked by de_ned relations making it possible to combine data from several tables on request. The SQL part of MySQL stands for "Structured Query Language" - the most common standardized language used to access databases.

MySQL is Open Source Software.

Open source means that it is possible for anyone to use and modify. Anybody can download MySQL from the Internet and use it without paying anything. Anybody so inclined can study the source code and change it to _t their needs. MySQL uses the GPL (GNU General Public License) http://www.gnu.org, to de_ne what you may and may not do with the software in di_erent situations. If you feel uncomfortable with the GPL or need to embed MySQL into a commercial application you can buy a commercially licensed version from us.

Why use MySQL?

MySQL is very fast, reliable, and easy to use. If that is what you are looking for, you should give it a try. MySQL also has a very practical set of features developed in very close cooperation with our users. You can _nd a performance comparison of MySQL to some other database managers on our benchmark page. See Section 12.7 [Benchmarks], page 355.

MySQL was originally developed to handle very large databases much faster than existing solutions and has been successfully used in highly demanding production environments for several years. Though under constant development, MySQL today o_ers a rich and very useful set of functions. The connectivity, speed, and security make MySQL highly suited for accessing databases on the Internet.

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MySQL-PHP

SOON WE WILL HEAD OFF on a fabulous journey, a journey on which we will explore the ins and outs of MySQL and PHP database applications in great detail. It’s going to be a fun trip; we just know it.

OK, maybe we’re being a bit optimistic. If you’re anything like us, there will be points when this particular journey will be a lot more tedious than it is exciting. Let’s face facts: application development isn’t always the most exciting thing in the world. And as with any other venture that involves programming, there are sure to be some very frustrating times, whether because of a syntax error you can’t find or a piece of code that won’t do what you think it ought to do. But despite all that, here you are, and I think there is a very good reason for your being here. Web applications are the present and the future. No matter your background, whether it be Visual Basic or COBOL, or maybe you know just some HTML and JavaScript, your résumé is only going to improve with some Web applications development experience. We don’t think there’s a better combination of tools to have under your belt than PHP and MySQL. The numbers bear us out. PHP and MySQL are becoming increasingly popular, and the demand for people who can use these tools will only increase.

But a bit later there will be more details on why you should use PHP and MySQL. Before we can get into the details of that, we want take a bit of time to go over the architecture of Web applications. Once we’ve done this, we will be able to explain in detail why PHP and MySQL should be the centerpieces of your application development environment. Once we’ve sold you on these tools, we’ll present a very quick and grossly under-coded application. As you look over this application, you will see the basic syntax and principles behind PHP and MySQL.

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mySQL Manual

This is the MySQL reference manual; it documents MySQL Version 4.0.1-alpha. Being a reference manual, it does not provide general instruction on SQL or relational database concepts.

As MySQL is work in progress, the manual gets updated frequently. The most recent version of this manual is available at http://www.mysql.com/documentation/ in many di_erent formats, currently there are Texinfo, plain text, Info, HTML, PostScript, and PDF versions. The primary document is the Texinfo _le. The HTML version is produced automatically using a modi_ed version of texi2html. The plain text and Info versions are produced with makeinfo. The Postscript version is produced using texi2dvi and dvips. The PDF version is produced with pdftex.

If you have a hard time _nding information in the manual, you can try our searchable PHP version at http://www.mysql.com/doc/.If you have any suggestions concerning additions or corrections to this manual, please send them to the manual team at docs@mysql.com.

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Teach Yourself SQL in 21 Days

The history of SQL begins in an IBM laboratory in San Jose, California, where SQL was developed in the late 1970s. The initials stand for Structured Query Language, and the language itself is often referred to as "sequel." It was originally developed for IBM's DB2 product (a relational database management system, or RDBMS, that can still be bought today for various platforms and environments). In fact, SQL makes an RDBMS possible. SQL is a nonprocedural language, in contrast to the procedural or thirdgeneration languages (3GLs) such as COBOL and C that had been created up to that time.

The characteristic that differentiates a DBMS from an RDBMS is that the RDBMS provides a set-oriented database language. For most RDBMSs, this set-oriented database language is SQL. Set oriented means that SQL processes sets of data in groups.

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Pengenalan MySQL

Apa Itu MySQL

MySQL (bisa dibaca dengan mai-es-ki-el atau bisa juga mai-se-kuel, terserah Anda) adalah suatu perangkat lunak database relasi (bahasa kerennya Relational Database Management System atau RDBMS), seperti halnya ORACLE, PostgreSQL, Microsoft SQL, dan sebagainya. MySQL jangan disalah-artikan dengan SQL. SQL (singkatan dari Structured Query Language) sendiri didefinisikan sebagai suatu sintaks perintah-perintah tertentu atau bahasa (program?) yang digunakan untukmengelola suatu database. jadi, MySQL dan SQL adalah dua 'mahluk' yang berbeda. Mudahnya, MySQL adalah softwarenya, danSQL adalah bahasa perintahnya. Jelas kan?

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Oracle 9i SQL Reference

Structured Query Language (SQL) is the set of statements with which all programs and users access data in an Oracle database. Application programs and Oracle tools often allow users access to the database without using SQL directly, but these applications in turn must use SQL when executing the user’s request. This chapter provides background information on SQL as used by most database systems.

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Oracle 9i database concepts

An Oracle database is a collection of data treated as a unit. The purpose of a database is to store and retrieve related information. A database server is the key to solving the problems of information management. In general, a server reliably manages a large amount of data in a multiuser environment so that many users can concurrently access the same data. All this is accomplished while delivering high performance. A database server also prevents unauthorized access and provides efficient solutions for failure recovery.

The database has logical structures and physical structures. Because the physical and logical structures are separate, the physical storage of data can be managed without affecting the access to logical storage structures.

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Oracle 9i Database Administrator's Guide

Oracle9i brings a major new release of the Oracle database server. It includes features to make the database more available. More online operations reduce the need for offline maintenance. Management of the database requires less effort. Oracle9i can automatically create and manage the underlying operating system files required by the database. There is a theme of self management.

Performance is enhanced. The Database Resource Manager has new options that allow for more granular control of resources. The performance level required of a resource consumer group can be better sustained. Partitioning enhancements allow tables and indexes to be better partitioned for performance. Security enhancements are an important part of this release. Applications have available more and finer grained methods of implementing security and auditing.

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Mengelola Tablespace & Data Files

Pada bab ini akan dibawah mengenai langkah-langkah administrasi database yang meliputi :

1. Mengerti struktur logika dari database
2. Membuat tablespace
3. Merubah ukuran tablespace
4. Merubah status dan setting peyimpanan tablespace
5. Menyiapkan tablespace yang diperlukan
   

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Mengelola Control File & Redo Log File

Pada bab ini akan dibawah mengenai langkah-langkah administrasi database yang meliputi :

1. Mengerti kegunaan dan mengetahui isi control file
2. Mendapatkan informasi control file

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Membuat Data Dictionary View

Pada bab ini akan dibawah mengenai langkah-langkah administrasi database yang meliputi :

1. Mengkonstruksi view untuk data dictionary
2. Menggunakan data dictionary
3. Menyiapakan lingkungan operasi PL/SQL menggunakan script administrativ
4. Melakukan administrasi terhadap store procedure dan paket

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Membuat Database

Pada bab ini akan dibawah mengenai langkah-langkah administrasi database yang meliputi :

1. Mempersiapkan sistem opersai
2. Mempersiapkan file parameter.
3. Membuat database.

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Mengelola Oracle Instance

Pada bab ini akan dibawah mengenai langkah-langkah administrasi database yang

meliputi :

1. Mengeset sistem operasi dan file pasword untuk atutentikasi.
2. Membuat file parameter.
3. Men-startup instance dan membuka database.
4. Menutup database dan men-shutdown instance.
5. Mendapatkan dan mengeset nilai parameter.
6. Mengelola session.
7. Memonitor ALERT dan trace files.

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Menggunakan Administration Tools

Pada bab ini akan dibawah mengenai langkah-langkah administrasi database yang dapat dilakukan dengan berbagai cara, antara lain :

1. Menggunakan program Server-Manager secara line-mode.
2. Mengidentifikasi apliaksi-aplikasi untuk keperluan administrasi yang mendukung Oracle Enterprise Manager.
   
3. Menggunakan komponen Oracle Enterprise Manager.

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Arsitektur Oracle

Server Oracle merupakan sistem ORDBMS (object-relational database management system) yang yang dilengkapi dengan sarana manajement informasi yang terbuka, komprehensif dan terintegrasi.

Pada bab ini akan diberikan wawasan mengenai komponen-komponen yang membentuk arsitektur server Oracle serta beberapa hal mengenai :

• Struktur yang membentuk koneksi antara user dan server Oracle

• Tahapan yang dilakukan oleh server Oracle pada saat memproses query.

• Tahapan yang dilakukan oleh server Oracle pada saat memproses statement

DML.

• Tahapan yang dilakukan oleh server Oracle pada saat memproses COMMIT.

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computer networking

Jaringan computer adalah kumpulan beberapa computer (dan perangkat lain seperti printer, hub dan sebagainya) dan saling terhubung satu sama lain melalui media perantara. Media perantara ini bisa berupa media kabel atau media tanpa kabel (nirkabel). Informasi berupa data akan mengalir dari satu komputer ke komputer lainnya atau dari satu komputer ke perangkat lain, sehingga masing – masing komputer yang terhubung tersebut bisa saling bertukar data atau berbagi berbagi perangkat keras.

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topologi jaringan

Topologi jaringan atau arsitektur jaringan adalah gambaran perencanaan hubungan antar computer dalam local area network yang umumnya menggunakan kabel (sebagai media transmisi), dengan konektor, Ethernet card, dan perangkat pendukung lainnya.

Ada beberapa jenis topologi yang terdapat pada hubungan computer pada jaringan local area, seperti :

Topologi bus, topologi ring, topologi start, extended start topology, tree topology, mesh topology serta kelebihan dan kekurangan dari tiap2 topology.

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Peralatan Jaringan

Di dalam membentuk suatu jaringan, baik itu bersifat LAN (local area network) maupun WAN (Wide Area Network ), kita membutuhkan media baik hardware maupun software. Beberapa media hardware yang penting di dalam membangun suatu jaringan, silahkan di download ajaaa….


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Peer to Peer and Client Server

Dua unit computer dikatakan terkoneksi apabila keduanya bisa saling brtukar data atau informasi, berbagi resource yang dimiliki, seperti file, printer, media penyimpanan (harddisk, floppy disk, cd-rom, flash disk,dll). Data yang berupa teks, audio, maupun video bergerak melalui media kabel atau tanpa kabel sehingga memungkinkan pengguna computer dalam jaringan computer dapat saling bertukar file/data, mencetak pada printer yang sama dan menggunakan hardware/software yang terhubung dalam jaringan secara bersama sama.

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E-Mail

Layanan elektronik mail (e-mail) merupakan salah satu aplikasi internet yang paling sering digunakan oleh para pengguna internet untuk dapat berkirim surat kepada user lain di tempat yang berbeda.

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langkah membuat friendster

Bagi anda yang belum memiliki friendster karena alasan tidak tau cara mendaftar, jangan berkecil hati karena penulis masih menyempatkan waktu untuk membuat tutorial cara mendaftar friendster. Dengan adanya friendster, kita bisa terhubung dengan friendster lain dengan syarat kita harus meng-add friendster teman kita. Intinya kita bisa bertemu dengan teman lama kita itupun kalo dia punya friendster, bisa juga untuk nyolong foto orang yang kita cidaha “cinta dalam hati” hahaaaaa…….

Jadi males nih kebanyakan ngomong langsung download aja yaaaaaaa……..

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Panduan pelatihan internet dasar

Internet adalah sumber daya informasi yang menjangkau seluruh dunia dimana antara satu komputer dengan komputer lain di dunia dapat saling berhubungan atau berkomunikasi.Berbagai manfaat dapat diperoleh dari internet, khususnya dalam dunia bisnis atau perusahaan.Internet merupakan forum global yang tidak membatasi negara, birokrasi, manusia, dan waktu, sehingga antar manusia dapat saling bertukar informasi dan dapat memberdayakan informasi tersebut.

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Panduan mencari informasi melalui internet

Teknik Jitu, Mencari Informasi dengan Search Engine Internet berisi misteri 1001 informasi. Mulai dari resep dapur, memilih nama bayi, horoskop, informasi teknologi, lelang, jual-beli buku sampai kegiatan ekspor-impor secara global ada di internet. Tapi bagaimana mencari informasi / situs yang sedang Anda butuhkan?

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Pengenalan internet

Internet adalah jaringan komputer dunia yang mengubungkan jaringan-jaringan computer regional di seluruh dunia. Di dalam internet terdapat jaringan kerja khusus berisi dokumen dokumen yang saling berhubungan yang dikenal dengan World Wide Web. WWW adalah fasilitas di internet yang mampu menampilkan informasi secara grafis dan interaktif yang tersusun dari rangkaian hubungan dari satu sumber dengan sumber yang lain di internet dan memungkinkan siapapun untuk berada 24 jam/hari di internet.

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cara buat e-mail yahoo

Email, apa itu email??? istilah ini sering sekali kita dengar. bagi orang tertentu mungkin sudah mengerti apa itu email , tapi ada juga beberapa orang yang belum mengerti istilah email. Email merupakan singkatan dari Electronic Mail, atau dalam bahasa Indonesianya Surat Elektronik, yaitu surat yang pengirimannya menggunakan sarana elektronik yaitu dengan jaringan internet, dengan surat elektronik atau email ini seseorang dapat mengirim naskah teks, gambar, atau bahkan mengirimkan aplikasi atau file kepada seseorang yang tentunya juga memiliki email (surat elektronik) dalam waktu yang sangat singkat. Karena email ini menggunakan jaringan internet, maka alamatnya pun juga menyesuaikan dengan penyedia layanan email di internet. Contoh penyedia layanan email adalah www.mail.yahoo.com, www.mail.google.com, dll.

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trik membuat "Strong Password"

Saat ini dengan banyaknya account yang kita miliki, mulai dari email, website, login bank, dan login ke account penting di Internet lainnya, mengharuskan kita membuat password yang cukup kuat, agar keamanan lebih terjamin. Apalagi jika account tersebut menyangkut informasi yang sangat penting, maka harus lebih memperhatikan masalah password ini.

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mempercepat waktu delay komputer

Ketika kita mengklik menu start trus memilih menu lain untuk membukanya, biasanya ada jeda waktu yang cukup lama (meskipun hanya beberapa detik). Dari saat kita mengklik sampai menu itu benar benar tampil di layar secara penuh. Secara default, kecepatan menu akan terbuka setelah kita mengklik menu itu selama 400milidetik. Kita bisa mengatur cepat lambatnya menu ini. Pingin tau caranya langsung aja download

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mencegah masuknya virus ke komputer

Saat anda memasukkan sebuah CD atau FLASHDISK ke dalam computer, biasanya CD atau FLASHDISK itu akan dieksekusi atau dibuka oleh system MS windows XP. Hal ini yang sering disebut dengan istilah “auto run dan auto play”. Perlu anda ketahui ada beberapa virus yang menggunkan fasilitas auto run ini, jadi saat anda memasukkan CD atau FLAShDISK yang mengandung virus, virus tersebut dapat ikut tereksekusi oleh system sehingga virus itu dapat langsung menyebar di computer anda. Berikut cara mematikan auto run:

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Administrasi pada Windows

Salah satu fasilitas yang tersedia dalam Windows XP adalah Anda dapat menentukan pemakai dengan format dan setting sesuai dengan keinginan, bahkan pada setiap pemakai dilengkapi dengan kata sandi (password) tersendiri. Dengan fasilitas ini, maka data dan settings dari setiap pemakai computer akan ditempatkan tersendiri yang terpisah dengan pemakai lain.

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aplikasi DOS

DOS (Disk Operating System) adalah suatu program yang berfungsi untuk mengkonfigurasikan suatu komputer agar dapat menjalankan perintah yang diberikan sebagai masukan.
Operating system yang lazim dipergunakan adalah MS DOS, karena selain kapasitasnya yang kacil juga perintah-perintah yang dipergunakan relatif lebih mudah jika dibandingkan dengan system lainnya.

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menyelamatkan mydocument

Tutorial kali ini bisa dibilang sesuatu yang gampang namun sempat terlupakan. Pada kali ini penulis pingin berbagi ilmu dengan teman teman yang belum mengetahui cara ini. Kenapa kita menyelamatkan MyDocument???? Defaultnya semua file akan disimpan di MyDocument terlebih lagi jika kita berselancar di dunia maya. Saat kita menginstall computer directory MyDocument akan ikut terformat sehingga data yang berada didalam akan hilang.

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Control Unit (CU)

Control Unit merupakan bagian dari CPU yang berfungsi untuk :
1. Membaca dan mengintepresikan instruksi instruksi program.
2. Melangsungkan operasi komponen komponen processor internal.
3. Mengendalikan aliran program dan data ke dalam dan keluar RAM.
Control Unit terdiri dari decoder dan tiga register (program register, instruction register, dan general purpose register). Register merupakan area penyimpanan yang bekerja dengan kecepatan tinggi. Register menangani instruksi dan data pada kecepatan 10 kali lebih cepat dari pada cache memory dan digunakan untuk suatu variasi fungsi pengolahan. Decoder berfungsi mengintepresikan dan mengkodekan instruksi – instruksi program. Program register adalah register yang mengandung alamat dari instruksi yang akan dieksekusi. Instruction register adalah register yang mengandung instruksi yang sedang dieksekusi. Register memberikan fasilitas perpindahan instruksi dan data antara RAM, Control Unit, dan Arithmetic and Logic Unit.
Bahasa yang dimengerti computer (processor) adalah bahasa mesin. Setiap computer mempunyai siklus mesin. Kecepatan processor biasanya diukur dengan berapa lama waktu yang diperlukan siklus mesin. Interval waktu siklus mesin adalah total waktu instruksi (instruction timer) dan waktu eksekusi (execution time).

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Arithmetic and Logic Unit (ALU)

Arithmetic and Logic Unit (ALU) melaksanaka seluruh perhitungan (penambahan, pengurangan, perkalian, pembagian) dan operasi logika. Hasil dari operasi tersebut diletakkan didalam register yang disebut accumulator. ALU berfungsi untuk melakukan operasi arithmetic dan logic yang terbagi dalam 4 kelas, yaitu : decimal arithmetic, fixed point arithmetic, floating point arithmetic, dan logic operation.
Decimal Arithmetic digunakan untuk operasi komersial dan dinyatakan dalam bilangan decimal dengan memakai tanda (+) untuk bilangan positif serta tanda (-) untuk bilangan negative. Fixed Point Arithmetic adalah untuk operasi Arithmetic dari data binary dan untuk menyatakan address dari storage. Floating Point Arithmetic untuk operasi matematika. Logic Operation dapat berupa operasi – operasi perbandingan, testing, translating, editing, dan moving logic data. Biasanya CPU dilengkapi dengan Internal Timer dan Time of Day Clock. Internal Timer akan mengukur internal processing time, yaitu berupa lama program itu bekerja. Time of Day Clock digunakan untuk mengukur dan menyatakan waktu (hari), jam dan detik. Waktu yang dapat dikumpulkan 142 tahun dan clock tersebut bekerja secara binary.

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CPU ( Central Processing Unit / Processor )

CPU merupakan jantung komputer karena CPU merupakan pusat kendali dari system computer. CPU disebut juga dengan processor.CPU berfungsi untuk :

1. Memberikan address data dan program

2. Memasukkan data dan mengambil data

3. Memproses data secara Arithmetic dan Logical.

4. Melaksanakan instruksi instruksi secara berturut turut.

CPU dapat merupakan penghubung antara internal storage dan input / output device. CPU terdiri dari Arithmetic dan Logic Unit (ALU), dan control unit (CU). Dalam system computer, CPU merupakan elemen yang paling penting. Pada mesin yang besar, CPU membutuhkan Printed Circuit Board (PCB).

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Unit keluaran ( output unit )

Output device adalah piranti tempat mengeluarkan hasil proses komputer. Fungsi dari output device :
1. Tempat keluarnya hasil proses
2. Menerjemahkan bit bit ke dalam kode yang dikenal media output.
Pada komputer, unit output dapat berbentuk tampilan, cetakan, grafik, suara, video dan animasi.

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Unit masukkan (input unit)

Input unit adalah peranti untuk memasukkan data dan program yang akan diproses di dalam komputer. Fungsi input unit adalah :
1. Tempat untuk memasukkan data dan program yang akan di proses.
2. Menerjemahkan kode kode yang dikenal oleh media input ke dalam kode kode yang dikenal komputer ( diubah menjadi binary digit / bit ).
3. Mengirim data yang sudah berupa bit bit ini kedalam sebuah storage.
Untuk memasukkan data ke dalam komputer digunakan sepuluh cara : melalui keyboard, alat penunjuk (point device ), alat pembaca optis atau magnetis, alat pembaca suara, sistem vision input, kamera digital, scanner, camcorder, snappy dan camera web.

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Hardware

Hardware atau perangkat keras komputer adalah alat pengolah data yang bekerja secara elektronis dan otomatis. Perangkat keras komputer dapat bekerja apabila ada unsur manusia yang mengerti tentang alat itu dan dapat bekerja menggunakan alat itu. Komputer merupakan sistem karena merupakan sekelompok objek yang berhubungan dan bekerjasama untuk menghasilkan sesuatu yang diinginkan.

Sistem perangkar keras komputer terdiri dari 4 unsur utama dan satu unsur tambahan. Keempat unsur utama itu adalah input unit, central processing unit (cpu), storage/memory dan output unit. Sedangkan yang merupakan unsur tambahan adalah communication link.
Input unit merupakan bagian yang menerima dan memasukkan data dan instruksi. Central Processing Unit (CPU) merupakan bagian yang melaksanakan dan mengatur instruksi, termasuk menghitung dan membandingkan. Memory / Storage merupakan bagian yang berfungsi untuk menyimpan data dan instruksi. Output unit merupakan bagian yang berfungsi untuk mengeluarkan hasil proses. Communication Link merupakan bagian yang berkomunikasi dengan dunia luar

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Jenis Aplikasi lain

a. Multimedia Player, seperti WinAmp, XMMS, Power DVD, JetAudio,Windows Media Player, dll.
b. Hacker Tools, seperti Find Password, Keygen / Crack Software License, Scanning Port, dll.
c. Network & Security Application, seperti Firewall, Intruder Detections, Network Monitoring, dll.
d. PC Games Applications, dan masih banyak lagi.

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Communication Application

Aplikasi yang digunakan untuk membangun komunikasi antara satu komputer dengan komputer lain dalam jaringan komputer lokal maupun global.
Contoh :
1. E-Mail & Fax Appl
2. Remote Access
3. YM, ICQ, MSN
4. Terminal Emulation
5. Instant Messaging
6. Voice recognition
7. Web Browser
8. Internet Telephony, dll.

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Development Tools

Merupakan sistem bahasa pemrograman komputer yang dilengkapi dengan kompiler tertentu sebagai sumber media penyusunan program aplikasi.
Contoh :
1. QuickBasic
2. Clipper
3. Visual Basic
4. Turbo Pascal
5. Visual C++
6. Turbo Assembler
7. GCC
8. Phyton
9. KDEvelopt
10 Gdesktop, dll.
Termasuk dalam jenis aplikasi ini adalah web development tools, yaitu aplikasi yang digunakan untuk membuat atau mendesain tampilan website (homepage) di internet, seperti FrontPage, Macromedia Dreamweaver, PHPedit, WebPage Editor, dll.

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Antivirus & Utility Tools

Software ini digunakan untuk operasi minor ( background ) yang bekerja dibelakang system, berguna untuk meningkatkan kinerja system operasi atu aplikasi dan juga performa hardware.
Terdapat 2 jenis utilitas di dalam system operasi :
1. Utilitas Internal, sudah termasuk dalam paket diinstalasi dalam system operasi seperti scandisk di windows atau perintah fsck ( file system check ) di OS linux.
2. Utilitas Eksternal, yang harus diinstalasi kemudian pad OS, seperti System Optimizer, PC Tools, Data / File Recovery, PC Maintenance, Internet Utilities, Norton System Work, Registry Clean & Repair, Hardware Repair.
Sementara untuk proteksi virus atau antivirus, contohnya : antivirus produk Mc Affee, Grisoft, Norton, PandaSoft, dll.

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Graphic Design

Aplikasi yang digunakan untuk membuat sketsa dua dimensi untuk desain ruangan, perabotan, mesin – mesin model industri, juga model tubuh manusia, hewan, dll.
Contoh :
1. AutoCad
2. Pro Design
3. Corel Draw
4. Adobe Ilustrator, dll.
Ada juga yang memasukkan dalam golongan ini aplikasi image, audio, video, manipulator, yaitu aplikasi yang digunakan untuk mengolah citra, suara hingga gambar 3 dimensi untuk pembuatan animasi, pengolahan amige, photo, audio, video editing, dll.
Contoh
1. Adobe Photoshop, After Effect, Premier, & Audition.
2. Corel Draw, Corel RAVE, Corel Photo Paint
3. Ulead Media Studio
4. GIMP ( in LINUX )
5. Cool Edit Pro, Sound Force
6. Macromedia Flash, Director
7. 3D Studio Max, Maya,dll.

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Database Application

Aplikasi yang digunakan dalam pengolahan data baik yang berukuran kecil maupun besar bisa digunakan secara stand-alone (tunggal) maupun dalam sistem berbasis jaringan lokal client server maupun webbase (intranet maupun internet).

Contoh :
1. MS SQL
2. FoxBase
3. Oracle
4. MySQL
5. PostgressSQL
6. SQL Server, dll.

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Business & Office Application

Aplikasi perkantoran dipergunakan untuk menyelesaikan masalah pekerjaan kantor seperti mengetik ( word processing, document management ), membuat tabel kerja ( worksheet ), membuat database sederhana ( MS Acsess ) ataupun mengolah image/citra sederhana .
Contoh aplikasi perkantoran yang terpaket komplit :
1. Microsoft Office
2. Koffice
3. StarOffice
4. Abiword
5. Open Office
6. MS Office for MAC, dll.

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Sumber daya manusia ( brainware )

Aspek brainware merupakan penggolongan manusia sebagai subyek yang menangani sistem komputer. Ada beberapa profesi dalam dunia IT saat ini, di antaranya :

1. CEO ( Chief Excecutive Officer ) orang yang paling bertanggung jawab atas pengembangan sistem & IT pada sebuah perusahaan.

2. Operator : orang yang menangani secara langsung pengolahan data komputer.

3. Programer : orang yang menyusu instruksi/program pada komputer dengan menggunakan bahasa pemrograman tertentu, umumnya PC lokal maupun LAN.

4. System Analyst : orang yang menganalisa/ merangcang bentuk dan mengembangkan sistem serta membangun fasilitas komputer.

5. Network Analyst : orang yang merencanakan / merancang sebuah topology jaringan komputer, baik intranet maupun internet.

6. Administrator System : orang yang menangani fungsi manajerial sistem pada suatu jaringan komputer, melindungi dan memelihara koneksi antar komputer ( terutama server ).

7. Network Security Consultant : orang yang memberikan masukan / saran dan menguji keamanan jaringan komputer secarra profesional.

8. Network Engineer : orang yang membangun dan memelihara jaringan komputer ( LAN, MAN, WAN ).

9. Cabling Installation Technician : teknisi instalasi pengkabelan.

10. echnical Engineer : orang yang mengetahui masalah yang terjadi pada komputer secara teknis, baik itu mengenai hardware maupun software, biasanya disebut Technical Support.

11. Web Designer : orang yang menangani pembuatan tampilan informasi pada media internet.

12. Animator : orang yang membuat tampilan animasi untuk media iklan di televisi, film, dll.

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Perangkat lunak aplikasi

Perangkat lunak aplikasi merupakan program siap pakai yang digunakan untuk aplikasi di bidang tertentu. Aplikasi ini dibagi atas beberapa bidang, antara lain : Business & Office Application, Database Application, Graphic Design, AntiVirus & Utility Tools, Development Tools, Communication Application, Jenis Aplikasi lain.

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Perangkat lunak system operasi

Operating system software merupakan perangkat lunak yang berfungsi untuk mengkonfigurasi komputer agar dapat menerima berbagai perintah dasar yang diberikan sebagai masukan.

Contoh :

1. MS-DOS

2. LINUX

3. UNIX

4. FREE BSD

5. OS / 2

6. SUN OS ( JAVA )

7. WINDOWS

8. MACINTOSH

9. NOVELL, dll.

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Perangkat Lunak ( Software )

Perangkat lunak berfungsi sebagai pengatur aktivitas kerja komputer dan semua instruksi yang mengarah pada sistem komputer. Perangkat lunak menjembatani interaksi user dengan komputer yang hanya memahami bahasa mesin. Secara umum perangkat lunak ini dapat dibagi atas :

1. Operating system software

2. Application software

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Main memory ( main storage )

Main memory merupakan tempat atau media yang digunakan untuk menyimpan data yang akan atau yang sedang diolah oleh sistem komputer.

Main memory dapat dibagi atas dua bagian, yaitu :

1. ROM (Read Only Memory )

ROM merupakan memory permanen yang terdapat pada sistem komputer yang sudah disusun dan dibuat oleh pabrik, biasanya tidak untuk diubah oleh user komputer.

ROM terdiri dari program pokok untuk konfigurasi sistem komputer seperti BIOS, BASIC, dan BootStrap Loader. Sekarang ini ROM yang dipakai BIOS menggunakan teknology CMOS ( Complementary Mental Oxide Semiconductor ), yang dapat mengubah konfigurasi BIOS bila perlu sehingga pemakai komputer dapat mengubah sistem BIOS. ROM tetap berada didalam komputer pada saat apapun. Sinyal di dalam ROM ini yang mengatur segala tugas CPU saat komputer mulai diaktifkan.

2. RAM (Random Access Memory)

Semua data yang dimasukkan melalui alat input pada setiap aplikasi dimasukkan terlebih dahulu ke dalam main memory ini, yaitu dalam RAM. Data – data yang terdapat dalam RAM ini hanya bersifat sementara. Apabila komputer dimatikan maka data tersebut akan hilang.

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Sistem computer

Sebuah komputer dapat bekerja dengan melibatkan tiga hal utama. Dalam penggunaan komputer sehari – hari, ketiga hal utama ini akan sering kita temui, yaitu :
1. Hardware, perangkat keras.
2. Software, perangkat lunak.
3. Brainware, user atau sumber daya manusia.

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Definisi computer

Istilah computer mempunyai arti yang sangat luas dan berbeda bagi setiap orang. Menurut Blissmer (1985), computer adalah suatu alat elektronik yang mampu melakukan berbagai tugas, yaitu menerima input, memproses input sesuai dengan instruksi yang diberikan, menyimpan perintah – perintah dan hasil pengolahannya serta menyediakan output dalam bentuk informasi.
Sedangkan menurut Sanders (1985), computer adalah system elektronik untuk memanipulasi data dengan cepat dan tepat serta dirancang dan diorganisasikan supaya secara otomatis menerima dan menyimpan data input, memprosesnya, dan menghasilkan output berdasarkan instruksi – instruksi yang telah tersimpan di dalam memory.
Dapat disimpulkan bahwa computer adalah suatu peralatan elektronik yang dapat menerima input, mengolahnya menggunakan suatu program yang tersimpan di dalam memory computer dan mengeluarkan hasilnya menjadi informasi dan kemudian dapat menyimpan program dan hasil olahannya ke dalam media penyimpanan menjadi sebuah file.

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computer

A computer is a machine that manipulates data according to a list of instructions.
The first devices that resemble modern computers date to the mid-20th century (1940–1945), although the computer concept and various machines similar to computers existed earlier. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers(PC).[1] Modern computers are based on tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space.[2] Today, simple computers may be made small enough to fit into a wristwatch and be powered from a watch battery. Personal computers, in various forms, are icons of the Information Age and are what most people think of as “a computer”; however, the most common form of computer in use today is the embedded computer. Embedded computers are small, simple devices that are used to control other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and children’s toys.
The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity. It is difficult to identify any one device as the earliest computer, partly because the term “computer” has been subject to varying interpretations over time. Originally, the term “computer” referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device.
The history of the modern computer begins with two separate technologies - that of automated calculation and that of programmability.
Examples of early mechanical calculating devices included the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when.[3] This is the essence of programmability.
The “castle clock”, an astronomical clock invented by Al-Jazari in 1206, is considered to be the earliest programmable analog computer.[4] It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing automatic doors to open every hour,[5][6] and five robotic musicians who play music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed every day in order to account for the changing lengths of day and night throughout the year.[4]
The end of the Middle Ages saw a re-invigoration of European mathematics and engineering, and Wilhelm Schickard’s 1623 device was the first of a number of mechanical calculators constructed by European engineers. However, none of those devices fit the modern definition of a computer because they could not be programmed.
In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.
It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called “The Analytical Engine”.[7] Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.
Large-scale automated data processing of punched cards was performed for the U.S. Census in 1890 by tabulating machines designed by Herman Hollerith and manufactured by the Computing Tabulating Recording Corporation, which later became IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter.
During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers.

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Programs

In practical terms, a computer program may run from just a few instructions to many millions of instructions, as in a program for a word processor or a web browser. A typical modern computer can execute billions of instructions per second (gigahertz or GHz) and rarely make a mistake over many years of operation. Large computer programs comprising several million instructions may take teams of programmers years to write, thus the probability of the entire program having been written without error is highly unlikely.

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Control unit

The control unit (often called a control system or central controller) directs the various components of a computer. It reads and interprets (decodes) instructions in the program one by one. The control system decodes each instruction and turns it into a series of control signals that operate the other parts of the computer.[16] Control systems in advanced computers may change the order of some instructions so as to improve performance.

A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.

The control system’s function is as follows—note that this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU:

The control system’s function is as follows—note that this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU:

1. Read the code for the next instruction from the cell indicated by the program counter.

2. Decode the numerical code for the instruction into a set of commands or signals for each of the other systems.

3. Increment the program counter so it points to the next instruction.

4. Read whatever data the instruction requires from cells in memory (or perhaps from an input device). The location of this required data is typically stored within the instruction code.

5. Provide the necessary data to an ALU or register.

6. If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.

7. Write the result from the ALU back to a memory location or to a register or perhaps an output device.

8. Jump back to step (1).

Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as “jumps” and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow).

It is noticeable that the sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program - and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer that runs a microcode program that causes all of these events to happen.

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Arithmetic/logic unit (ALU)

The ALU is capable of performing two classes of operations: arithmetic and logic.

The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers—albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other (”is 64 greater than 65?”).

Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic.

Superscalar computers contain multiple ALUs so that they can process several instructions at the same time. Graphics processors and computers with SIMD and MIMD features often provide ALUs that can perform arithmetic on vectors and matrices.

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Memory

A computer’s memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered “address” and can store a single number. The computer can be instructed to “put the number 123 into the cell numbered 1357″ or to “add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595″. The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is up to the software to give significance to what the memory sees as nothing but a series of numbers.
In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers; either from 0 to 255 or -128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two’s complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory as long as it can be somehow represented in numerical form. Modern computers have billions or even trillions of bytes of memory.
The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. Since data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer’s speed.
Computer main memory comes in two principal varieties: random access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer’s initial start-up instructions. In general, the contents of RAM is erased when the power to the computer is turned off while ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer’s operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the software required to perform the task may be stored in ROM. Software that is stored in ROM is often called firmware because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM by retaining data when turned off but being rewritable like RAM. However, flash memory is typically much slower than conventional ROM and RAM so its use is restricted to applications where high speeds are not required.[18]
In more sophisticated computers there may be one or more RAM cache memories which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer’s part.

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Input/output (I/O)

Input & Output is the means by which a computer receives information from the outside world and sends results back. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O.

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Multitasking

While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by having the computer switch rapidly between running each program in turn. One means by which this is done is with a special signal called an interrupt which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running “at the same time”, then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed “time-sharing” since each program is allocated a “slice” of time in turn.
Before the era of cheap computers, the principle use for multitasking was to allow many people to share the same computer.
Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly - in direct proportion to the number of programs it is running. However, most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a “time slice” until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run at the same time without unacceptable speed loss.

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Multiprocessing

Some computers may divide their work between one or more separate CPUs, creating a multiprocessing configuration. Traditionally, this technique was utilized only in large and powerful computers such as supercomputers, mainframe computers and servers. However, multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers have become widely available and are beginning to see increased usage in lower-end markets as a result.
Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers.[19] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called “embarrassingly parallel” tasks.

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Networking and the Internet

Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military’s SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre.
In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET. The technologies that made the Arpanet possible spread and evolved. In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. “Wireless” networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.

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