Computer Worm

  • Computer worm

This article is about coding of a worm.

Hex dump of the Blaster worm, showing a message left for Microsoft CEO Bill Gates by the worm programmer

Spread of Conficker worm

A computer worm is a standalonemalware computer program that replicates itself in order to spread to other computers.

Often, it uses acomputer network to spread itself, relying on security failures on the target computer to access it.

Worms almost always cause at least some harm to the network, even if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.

Many worms that have been created are designed only to spread, and do not attempt to change the systems they pass through.

However, as the Morris worm and Mydoom showed, even these “payload-free” worms can cause major disruption by increasing network traffic and other unintended effects.

History

worm source code floppy diskette at the Computer History Museum

The actual term “worm” was first used in John Brunner’s 1975 novel, The Shockwave Rider.

In that novel, Nichlas Haflinger designs and sets off a data-gathering worm in an act of revenge against the powerful men who run a national electronic information web that induces mass conformity.

“You have the biggest-ever worm loose in the net, and it automatically sabotages any attempt to monitor it… There’s never been a worm with that tough a head or that long a tail!”

On November 2, 1988, Robert Tappan Morris, a Cornell University computer science graduate student, unleashed what became known as the Morris worm, disrupting a large number of computers then on the Internet, guessed at the time to be one tenth of all those connected.

During the Morris appeal process, the U.S. Court of Appeals estimated the cost of removing the virus from each installation at between $200 and $53,000; this work prompted the formation of the CERT Coordination Center and Phage mailing list.

Morris himself became the first person tried and convicted under the 1986Computer Fraud and Abuse Act.

Harm

Any code designed to do more than spread the worm is typically referred to as the “payload”.

Typical malicious payloads might delete files on a host system (e.g., the ExploreZip worm), encrypt files in a ransomware attack, orexfiltrate data such as confidential documents or passwords.

Probably the most common payload for worms is to install a backdoor.

This allows the computer to be remotely controlled by the worm author as a “zombie”.

Networks of such machines are often referred to as botnets and are very commonly used for a range of malicious purposes, including sendingspam or performing DoSattacks.

Countermeasures

Worms spread by exploiting vulnerabilities in operating systems.

Vendors with security problems supply regular security updates (see “Patch Tuesday”), and if these are installed to a machine then the majority of worms are unable to spread to it.

If a vulnerability is disclosed before the security patch released by the vendor, a zero-day attack is possible.

Users need to be wary of opening unexpected email,and should not run attached files or programs, or visit web sites that are linked to such emails.

However, as with the ILOVEYOU worm, and with the increased growth and efficiency of phishing attacks, it remains possible to trick the end-user into running malicious code.

Anti-virus and anti-spyware software are helpful, but must be kept up-to-date with new pattern files at least every few days.

The use of a firewall is also recommended.

In the April–June 2008 issue of IEEETransactions on Dependable and Secure Computing, computer scientists described a new and potentially effective way to combat internet worms.

The researchers discovered how to contain worms that scanned the Internet randomly, looking for vulnerable hosts to infect.

They found that the key was to use software to monitor the number of scans that machines on a network send out.

When a machine started to send out too many scans, it was a sign that it has been infected, which allowed administrators to take it off line and check it for malware.

In addition, machine learning techniques can be used to detect new worms, by analyzing the behavior of the suspected computer.

Users can minimize the threat posed by worms by keeping their computers’ operating system and other software up to date, avoiding opening unrecognized or unexpected emails and runningfirewall and antivirus software.

Mitigation techniques include:

  • ACLs in routers and switches
  • Packet-filters
  • TCP Wrapper/ACL enabled network service daemons
  • Nullroute

Worms with good intent

Beginning with the very first research into worms at Xerox PARC, there have been attempts to create useful worms.

Those worms allowed testing by John Shoch and Jon Hupp of the Ethernetprinciples on their network of Xerox Alto computers.

The Nachi family of worms tried to download and install patches from Microsoft’s website to fix vulnerabilities in the host system—by exploiting those same vulnerabilities.

In practice, although this may have made these systems more secure, it generated considerable network traffic, rebooted the machine in the course of patching it, and did its work without the consent of the computer’s owner or user.

Regardless of their payload or their writers’ intentions, most security experts regard all worms as malware.

Several worms, like XSS worms, have been written to research how worms spread.

For example, the effects of changes in social activity or user behavior.

One study proposed what seems to be the first computer worm that operates on the second layer of the OSI model (Data link Layer), it utilizes topology information such as Content-addressable memory (CAM) tables and Spanning Tree information stored in switches to propagate and probe for vulnerable nodes until the enterprise network is covered.

Computer Network

The Network Computer (or NC) was adiskless desktop computer device made by Oracle Corporation from approximately 1996 to 2000.

The devices were designed and manufactured by an alliance, which included Sun Microsystems, IBM, and others.

The devices were designed with minimum specifications, based on theNetwork Computer Reference Profile.

The brand was also employed as amarketing term to try to popularize this design of computer within enterprise and among consumers.

The NC brand was mainly intended to inspire a range of desktop computers from various suppliers that, by virtue of their diskless design and use of inexpensive components and software, were cheaper and easier to manage than standard fat client desktops.

However, due to the commoditization of standard desktop components, and due to the increasing availability and popularity of various software options for using full desktops as diskless nodes, thin clients, and hybrid clients, the Network Computer brand never achieved the popularity hoped for by Oracle and was eventually mothballed.

The term “network computer” is now used for any diskless desktop computeror a thin client.

History

re of the NC to impact on the scale predicted by Larry Ellison may have been caused by a number of factors.

Firstly, prices of PCs quickly fell below $1000, making the competition very hard.

Secondly, the software available for NCs was neither mature nor open.

Thirdly, the idea could simply have been ahead of its time, as at the NC’s launch in 1996, the typical home Internetconnection was only a 28.8 kbit/s modem dialup.

This was simply insufficient for the delivery ofexecutable content. The world wide webitself was not considered mainstream until its breakout year, 1998.

Prior to this, very few Internet service providersadvertised in mainstream press (at least outside of the USA), and knowledge of the Internet was limited. This could have held back uptake of what would be seen as a very niche device with no (then) obvious appeal.

Ironically, NCs ended up being used as the very ‘dumb terminals’ they were intended to replace, as theproprietary backend infrastructure is not readily available.

1990s era NCs are often network-booted into a minimal Unix with X, to serve as X terminal.

While NC purists may consider this to be a suboptimal use of NC hardware, the NCs work well as terminals, and are considerably cheaper than purpose-built terminal hardware.

NC standards and drafts

Reference Profile

The initial Network Computing standard, the Network Computer Reference Profile(NCRef), required that all ‘NC’ appliances supported HTML, Java, HTTP, JPEG, and other key standards.

Other standards

Because many NCs did not use IntelCPUs or Microsoft software, Microsoft and Intel developed a competing standard called NetPC.

Other alternatives to the NCRef were WeBRef(Motorola and HDS Network Systems) and Odin (National Semiconductor).

The HDS @workStation was stated to ship by the end of June 1996.

NC extensions

NC implementations

Acorn Network Computer

An Acorn NetStation NC

The Acorn Network Computer was Oracle’s initial reference implementationof the NC.

Its development was subcontracted to British company Acorn Computers,who adapted its ownRISC OS to create NCOS.

Acorn made use of local partner companies ANT,Icon Technology and Design Edge to fulfil their contract.

Macintosh NCE

In 1997 Apple announced the Mac NC, its attempt to develop the Pippin into a network computer platform.

By the end of 1997, Steve Jobs discontinued allMacintosh clone efforts, effectively killing the Pippin, although key components of the Mac NC technology were inherited by the original iMac.

NetProducts NetStation

The first generation NetStation design and the NetStation trademark was licensed to NChannel, which provided the consumer equipment and Internet service (with associated infrastructure) for the UK market. After a few months, NChannel split into two entities:NetChannel (which provided the Internet service) and NetProducts which provided the consumer hardware.

NetProducts started working with Acorn to develop a next-generation product, NetStation II and started developing anemail-only set-top-box (the TVemail).

NetProducts went into voluntaryliquidation in 1998 before either project was completed.

Sun Microsystems JavaStation

Sun Microsystems developed theJavaStation, a JavaOS-based NC based on SPARC hardware, initially similar to Sun’s range of Unix workstations.

IBM Network Station

hed its Network Station in September 1996.

As with the later reference design, the Network Station used a NetBSD-based NCOS booted over a LAN from an AS/400 or IBM PCserver.

The Network Station supported local execution of basic applications, such as a web browser and console.

In addition, X capability was also implemented to allow both locally and remotely run applications to be used on the same machine.

In practice, the lack of real applications meant that this was little more than a hardware X terminal.

The IBM Network Station was originally based on the PowerPC architecture, but the final few models used Intel Pentiumprocessors.

Contemporary analogy

Some see the idea behind the NC as existing in contemporary times in the system of cloud computing and in particular Google Chrome OS.

In Wired magazine, Daniel Roth claims that the failure of the network computer eventually led to the development of cloud computing.

A large contribution to this transition was attributed to Eric Schmidt, once the CTO of Sun Microsystems, a proponent of the network computer, who eventually became the CEO of Google.

Google is a large purveyor of cloud technology, “most notably Google Docs and Spreadsheets.”

Continue reading “Computer Network”

Computer Addiction

Computer addiction can be described as the excessive or compulsive use of the computer which persists despite serious negative consequences for personal, social, or occupational function.

Another clear conceptualization is made by Block, who stated that “Conceptually, the diagnosis is a compulsive-impulsive spectrum disorder that involves online and/or offline computer usage and consists of at least three subtypes: excessive gaming, sexual preoccupations, and e-mail/text messaging”.

While it was expected that this new type of addiction would find a place under the compulsive disorders in the DSM-5, the current edition of the Diagnostic and Statistical Manual of Mental Disorders, it is still counted as an unofficial disorder.

The concept of computer addiction is broadly divided into two types, namely offline computer addiction and online computer addiction.

The term offline computer addiction is normally used when speaking about excessive gaming behavior, which can be practiced both offline and online.

Online computer addiction, also known as Internet addiction, gets more attention in general from scientific research than offline computer addiction, mainly because most cases of computer addiction are related to the excessive use of the Internet.

Although addiction is usually used to describe dependence on substances, addiction can also be used to describe pathological Internet use.

Experts on Internet addiction have described this syndrome as an individual being intensely working on the Internet, prolonged use of the Internet, uncontrollable use of the Internet, unable to use the Internet with efficient time, not being interested in the outside world, not spending time with people from the outside world, and an increase in their loneliness and dejection.

However, simply working long hours on the computer does not necessarily mean someone is addicted.

Symptoms

  • Being drawn by the computer as soon as one wakes up and before one goes to bed.
  • Replacing old hobbies with excessive use of the computer and using the computer as one’s primary source of entertainment and procrastination
  • Lacking physical exercise and/or outdoor exposure because of constant use of the computer, which could contribute to many health problems such as obesity

Effects

Excessive computer use may result in, or occur with:

  • Lack of face to face social interaction
  • Computer vision syndrome

Causes

Kimberly Young indicates that previous research links internet/computer addiction with existing mental health issues, most notably depression.

She states that computer addiction has significant effects socially such as low self-esteem, psychologically and occupationally which led many subjects to academic failure.

According to a Korean study on internet/computer addiction, pathological use of the internet results in negative life impacts such as job loss, marriage breakdown, financial debt, and academic failure.

70% of internet users in Korea are reported to play online games, 18% of which are diagnosed as game addicts which relates to internet/computer addiction.

The authors of the article conducted a study using Kimberly Young’s questionnaire.

The study showed that the majority of those who met the requirements of internet/computer addiction suffered from interpersonal difficulties and stress and that those addicted to online games specifically responded that they hoped to avoid reality.

Types

Computers nowadays rely almost entirely on the internet and thus relevant research articles relating to internet addiction may also be relevant to computer addiction.

  • Gaming addiction: a hypotheticalbehavioral addiction characterized by excessive or compulsive use ofcomputer games or video games, which interferes with a person’severyday life.Video game addiction may present itself as compulsive gaming, social isolation, mood swings, diminished imagination, and hyper-focus on in-game achievements, to the exclusion of other events in life.
  • Social media addiction: Data suggest that participants use social media to fulfill their social needs, but are typically dissatisfied.Lonely individuals are drawn to the Internet for emotional support. This could interfere with “real life socializing” by reducing face-to-face relationships.Some of these views are summed up in an Atlantic article by Stephen Marche entitled Is Facebook Making Us Lonely?, in which the author argues that social media provides more breadth, but not the depth of relationships that humans require and that users begin to find it difficult to distinguish between the meaningful relationships which we foster in the real world, and the numerous casual relationships that are formed through social media.

Diagnostic Test

of studies and surveys are being conducted to measure the extent of this type of addiction. Dr.Kimberly S. Younghas created s questionnaire based on other disorders to assess the level of addiction.

It is called the Internet Addict Diagnostic Questionnaire or IADQ.

Answering positively to five out of the eight questions may be indicative of an online addiction.

Origin of the term and history

British e-learning academic Nicholas Rushby suggested in his 1979 book, An Introduction to Educational Computing, that people can be addicted to computers and suffer withdrawal symptoms.

The term was also used by M. Shotton in 1989 in her book Computer Addiction.

However, Shotton concludes that the ‘addicts’ are not truly addicted.

Dependency on computers, she argues, is better understood as a challenging and exiting pastime that can also lead to a professional career in the field.

Computers do not turn gregarious, extroverted people into recluses; instead they offer introverts a source of inspiration, excitement and intellectual stimulation.

Shotton’s work seriously questions the legitimacy of the claim that computers cause addiction.

The term became more widespread with the explosive growth of the Internet, as well the availability of the personal computer.

Computers and the Internet both started to take shape as a personal and comfortable medium which could be used by anyone who wanted to make use of it.

With that explosive growth of individuals making use of PCs and the Internet, the question started to arise whether or not misuse or excessive use of these new technologies could be possible as well. It was hypothesized that, like any technology aimed specifically at human consumption and use, that abuse could have severe consequences for the individual in the short term and for the society in the long term.

In the late nineties people who made use of PCs and the internet where already referred to the term webaholics or cyberholics. Pratarelli et al.

Suggested at that point already to label “a cluster of behaviors potentially causing problems” as computer or Internet addiction.

There are other examples of computer overuse that date back to the earliest computer games.

Press reports have furthermore noted that some Finnish Defence Forces conscripts were not mature enough to meet the demands of military life, and were required to interrupt or postpone military service for a year.

One reported source of the lack of needed social skills is overuse of computer games or the Internet.

Forbes termed this overuse “Web fixations”, and stated that they were responsible for 12 such interruptions or deferrals over the 5 years from 2000–2005.

 

CDDB

CDDB, short for Compact Disc Database, is a database for softwareapplications to look up audio CD (compact disc) information over theInternet.

This is performed by a client which calculates a (nearly) unique discID and then queries the database.

As a result, the client is able to display the artist name, CD title, track list and some additional information. CDDB is a licensed trademark of Gracenote, Inc.

The database is used primarily bymedia players and CD ripper software.

If a CD is not recognized by a media player or CD ripper it can be added to the database if the user fills in the names and artists etc.

in a media player such as iTunes or MusicMatch Jukebox.

The need for CDDB is a direct consequence of the original design of the CD, which was conceived as an evolution of the gramophone record, and did not consider the audio tracks as data files to be identified and indexed.

The audio CD format does not include the disc name or track names, so a supplemental database is needed to supply this information when discs are used with modern media systems.

A later development called CD-Text is another solution to the same problem.

 

History

CDDB was invented by Ti Kan around late 1993 as a local database that was delivered with his popular xmcd music player application.

The application’s change history first mentions the acronym CDDB in version 1.1 released on February 25, 1994.

Users would submit new entries to the database via e-mail to Kan.

The database quickly became unwieldy and Kan enlisted the help of Steve Scherf to create a network accessible version of the database operating as CDDB Inc. In 1995.

Graham Toal supplied hosting for the CDDB server and created a banner advertising revenue model to pay for the hosting.

The original software behind CDDB was released under the GNU General Public License, and many people submitted CD information thinking the service would also remain free.

The project was eventually incorporated as CDDB LLC in 1998 and was soon sold by Kan, Scherf, and Toal to a high tech consumer electronics manufacturer called Escient.

In a 2006 interview in Wired, Scherf claimed that Escient was the only company that would guarantee the continued development of the service by its founders, as well as protect the operation in an atmosphere where numerous companies were bidding—and in one case, attempting extortion—to acquire and immediately sell the CDDB to major players like Microsoft, which wanted a CD-recognition service but wouldn’t deal directly with CDDB Inc.

In 2000, CDDB Inc. was renamed Gracenote.

Early announcements asserted that access to the CDDB service would “remain 100% free to software developers and consumers.”

The license was nonetheless changed, and some programmers complained that the new license included certain terms that they couldn’t accept.

If one wanted to access CDDB, one was not allowed to access any other CDDB-like database such as freedb.

Any programs using a CDDB lookup had to display a CDDB logo while performing the lookup.

In March 2001, CDDB, now owned by Gracenote, banned all unlicensed applications from accessing their database. New licenses for CDDB1 (the original version of CDDB) were no longer available, since Gracenote wanted to force programmers to switch to CDDB2, a new version incompatible with CDDB1 and hence with freedb.

The license change motivated many forks in the CDDB project tree, including the freedb project, which is intended to remain free software.

As of June 2, 2008, Sony Corp. of America completed acquisition (full ownership) of Gracenote, per the news note on the Gracenote website.

How CDDB works

CDDB was designed around the task of identifying entire CDs, not merely single tracks.

The identification process involves creating a “discid”, a sort of “fingerprint” of a CD created by performing calculations on the track duration information stored in the table-of-contents of the CD (see the following section for an example calculation).

This discid is used with the Internet database, typically either to download track names for the whole CD or to submit track names for a newly identified CD.

This information is often provided byend users.

In iTunes, which uses Gracenote, users name the CD tracks and then use the “Submit Track Names” option under the “Advanced” heading in the toolbar to submit track information.

Since identification of CDs is based on the length and order of the tracks, CDDB cannot identify playlists in which the order of tracks has been changed, or compilations of tracks from different CDs.

CDDB also cannot distinguish between different CDs that have the same number of tracks and the same track lengths.

Example calculation of a CDDB1 (FreeDB) disc ID

CDDB1 identifies CDs with a 32-bit number, usually displayed as a hexadecimal number containing 8 digits: XXYYYYZZ. The first two digits (labeled XX) represent a checksum based on the starting times of each track on the CD, mod 255.

The next four digits (YYYY) represent the total time of the CD in seconds from the start of the first track to the end of the last track.

The last two digits (ZZ) represent the number of tracks on the CD.

For example, suppose a CD contains a single track of duration 3610 seconds.

First the XX checksum is calculated by summing the track starting times mod 255.

Since CDs have a 2-second offset from the start of disc data, XX becomes “02”.

Second, the total CD play duration of 3610 seconds in hexadecimal is 0e1a, so YYYY becomes “0e1a”.

Finally, there is one track on this CD so ZZ becomes “01”.

The full disc ID of the example CD is “020e1a01”.

Any CD which contains one track with a duration of 3610 seconds starting 2 seconds from the beginning of the CD will have this disc ID.

To distinguish between different CDs which happen to have the same disc ID, the CDDB1 database is organized into multiple categories.

If there is a conflict with different CD releases possessing the same CDDB1 ID, they can be placed in a different category (such as classical, rock, blues, folk or misc).

Sample code for calculating CDDB1 disc IDs in various programming languages is available on the web, such as in Java.

Classical music

At its origin, CDDB was oriented towards pop/rock music with the typical artist/album/song structure.

Their database often lacks adequate information on classical music CDs, mostly due to its structure, which originally lacked a standard way of storing composers’ names.

In 2007, Gracenote announced an enhanced format, the Classical Music Initiative (CMI), which places all the additional information in the three-field structure. A classical track title would now contain the composer, for instance “Vivaldi: The Four Seasons, Op. 8/1, ‘Spring’ — 1. Allegro”.

The artist field would contain all information about the ensemble, conductor and perhaps soloist, for instance “Joseph Silverstein, Seiji Ozawa, Boston Symphony Orchestra”.

In 2007, about 10,000 classical CDs had been converted to this new convention.

Alternatives

Alternative projects include freedb,MusicBrainz, Discogs, Decibel Music Systems Ltd and AMG LASSO.

Komputer ( Bagian 3 )

PENGGUNAAN KOMPUTER

Komputer digital pertama, memiliki ukuran yang besar dan membutuhkan biaya besar untuk pembuatannya.

Komputer pada masa itu umumnya digunakan untuk mengerjakan perhitungan ilmiah.

ENIAC, komputer awal AS awalnya dibuat untuk memperhitungkan tabel ilmu balistik untuk persenjataan (artileri), menghitung kerapatan penampang neutron untuk melihat jika bom hidrogen akan bekerja dengan semestinya (perhitungan ini, yang dilakukan pada Desember 1945 sampai Januari 1946 dan melibatkan dala dalam lebih dari satu juta kartu punch, memperlihatkan bentuk lalu di bawah pertimbangan akan gagal).

CSIR Mk 1/CSIRAC, komputer pertama Australia, mengevaluasi pola curah hujan untuk tempat penampungan dari Snowy Mountains, suatu proyek pembangkit Hidroelektrik besar.

Selain itu juga dipakai dalam kriptanalisis, misalnya komputer elektronik digital yang pertama, Colossus, dibuat selama Perang Dunia II.

Akan tetapi, visionaris awal juga menyangka bahwa pemrograman itu akan dapat memainkan catur, memindahkan gambar dan penggunaan lain.

Orang-orang di pemerintah dan perusahaan besar juga memakai komputer untuk mengotomasikan banyak data dan mengerjakan tugas yang sebelumnya dikerjakan oleh manusia – misalnya, memelihara dan memperbarui rekening dan inventaris.

Dalam bidang pendidikan, ilmuwan di berbagai bidang mulai memakai komputer untuk analisis mereka sendiri.

Penurunan harga komputer membuat komputer dapat dipakai oleh organisasi yang lebih kecil.

Bisnis, organisasi, dan pemerintah sering menggunakan banyak komputer kecil untuk menyelesaikan tugas yang sebelumnya dilakukan oleh komputer kerangka utama yang mahal dan besar.

Kumpulan komputer yang lebih kecil di satu lokasi disebut sebagai server.

Dengan penemuan mikroprosesor di 1970-an, menghasilkan komputer yang sangat murah menjadi mungkin.

PC menjadi populer untuk banyak tugas, termasuk menyimpan buku, menulis, dan mencetak dokumen.

Perhitungan meramalkan dan lain berulang matematika dengan lembarang sebar, berhubungan dengan e-pos dan,Internet.

Namun, ketersediaan luas komputer dan mudah dikostumisasi komputer dapat digunakan untuk banyak pekerjaan lain.

Sekaligus, komputer kecil, biasanya dengan mengatur program, ditemukan cara mengaplikasikan mereka ke dalam alat lain seperti peralatan rumah, mobil, pesawat terbang, dan perlengkapan industri.

Prosesor benam menguasai kelakuan alat seperti itu yang lebih mudah, membolehkan kelakuan kontrol yang lebih kompleks (untuk kejadian, perkembangan sistem rem anti terkuncidi mobil).

Saat abad kedua puluh satu dimulai, kebanyakan alat listrik, bentuk angkutan bertenaga, dan batas produksi pabrik dikuasai di sisi komputer.

Kebanyakan insinyur memprediksikan bahwa ini akan terus berkembang.

Bagian-bagian komputer

Komputer terdiri atas 2 bagian besar yaitu perangkat lunak (software) dan perangkat keras (hardware).

Perangkat keras

  • Pemroses atau CPU sebagai unit pengolah data
  • Memori RAM, tempat penyimpanan data sementara
  • Hard drive, media penyimpanan data semi permanen
  • Perangkat masukan, media yang digunakan untuk memasukkan data untuk diproses oleh CPU, seperti : mouse, keyboard, dan tablet
  • Perangkat keluaran, media yang digunakan untuk menampilkan hasil keluaran pemrosesan CPU, seperti :monitor, speaker, headset, plotter,proyektor, dan printer

Perangkat lunak

  • Sistem operasi
    Program dasar pada komputer yang menghubungkan pengguna dengan hardware komputer. Sistem operasi yang biasa digunakan adalah Linux,Windows, dan Mac OS. Tugas sistem operasi termasuk (namun tidak hanya) mengatur eksekusi program di atasnya, koordinasi input, output, pemrosesan, memori, serta instalasi software.
  • Program komputer
    Merupakan aplikasi tambahan yang dipasang sesuai dengan sistem operasinya

Slot pada komputer untuk masukan kartu tambahan non-grafis

  • AGP/PCIe, slot untuk masukan kartu tambahan grafis
  • IDE/SCSI/SATA, slot untuk hard drive/ODD
  • USB, slot untuk masukan media plug-and-play (colok dan mainkan, artinya perangkat yang dapat dihubungkan ke komputer dan langsung dapat digunakan)

Jenis komputer

  • Komputer analog
  • Komputer pulsa
  • Mikrokomputer
    • Komputer rumah (home computer)
    • Komputer pribadi (PC)
    • Server
  • Minikomputer
  • Mainframe computer
  • Superkomputer