Editing MIDI (section)

====Computer files====
[[File:Bach- Crab Canon from the Musical Offering.webm|thumb|MIDI files contain sound events such as a finger striking a key, which can be visualized using  software such as [[Synthesia (video game)|Synthesia]].]]

A MIDI file is not an audio recording. Rather, it is a set of instructions{{snd}}for example, for pitch or tempo{{snd}}and can use a thousand times less disk space than the equivalent recorded audio.<ref name="Crawford">Crawford, Walt. "MIDI and Wave: Coping with the Language". ''Online''. Vol. 20, No. 1. Jan/Feb 1996</ref><ref>{{citation |last=Aboukhadijeh |first=Feross. |url=https://feross.org/bitmidi/ |title=Announcing BitMidi |date=Aug 2018 |access-date=18 November 2018 |archive-date=4 October 2018 |archive-url=https://web.archive.org/web/20181004230746/https://feross.org/bitmidi/ |url-status=live }}</ref> Due to their tiny filesize, fan-made MIDI arrangements became an attractive way to share music online, before the advent of [[broadband internet access]] and multi-gigabyte hard drives.<ref>{{cite web |url=https://www.vice.com/en/article/the-internets-first-hit-file-format-wasnt-the-mp3-it-was-midi/ |title=The Internet's First Hit File Format Wasn't the MP3. It Was MIDI |date=8 November 2019 |access-date=2020-10-12 |archive-date=4 December 2020 |archive-url=https://web.archive.org/web/20201204091322/https://www.vice.com/en/article/a359xe/the-internets-first-hit-file-format-wasnt-the-mp3-it-was-midi |url-status=live }}</ref> The major drawback to this is the wide variation in quality of users' audio cards, and in the actual audio contained as samples or synthesized sound in the card that the MIDI data only refers to symbolically. Even a sound card that contains high-quality sampled sounds can have inconsistent quality from one sampled instrument to another.<ref name="Crawford" /> Early budget-priced cards, such as the [[AdLib]] and the [[Sound Blaster]] and its compatibles, used a stripped-down version of Yamaha's [[frequency modulation synthesis]] (FM synthesis) technology<ref name="WiffenFM">Wiffen, Paul. "[http://www.soundonsound.com/sos/1997_articles/sep97/synthschool3.html Synth School, Part 3: Digital Synthesis (FM, PD & VPM)] {{webarchive|url=https://web.archive.org/web/20051201090629/http://www.soundonsound.com/sos/1997_articles/sep97/synthschool3.html |date=1 December 2005 }}". ''Sound on Sound'' Sep 1997. Print.</ref> played back through low-quality digital-to-analog converters. The low-fidelity reproduction<ref name="Crawford" /> of these ubiquitous<ref name="WiffenFM" /> cards was often assumed to somehow be a property of MIDI itself. This created a perception of MIDI as low-quality audio, while in reality MIDI itself contains no sound,<ref name="Battino">Battino, David. ''[http://blogs.oreilly.com/digitalmedia/2005/10/finally-midi-20.html Finally: MIDI 2.0] {{webarchive|url=https://web.archive.org/web/20120816000340/http://blogs.oreilly.com/digitalmedia/2005/10/finally-midi-20.html|date=16 August 2012}}'' O'Reilly Digital Media Blog. O'Reilly Media, Inc. 6 October 2005. Web. 22 August 2012</ref> and the quality of its playback depends entirely on the quality of the sound-producing device.<ref name="Brewster" />{{rp|227|date=November 2012}}

{{Infobox file format
| name                   = Standard MIDI File
| extensions             = {{code|.mid}} {{code|.midi}} {{code|.smf}}  (Standard MIDI File) {{code|.rmi}}  (RIFF MIDI)
| mime                   = {{code|audio/midi}} {{code|audio/x-midi}}
| type_code              = Midi
| uniform type           = public.midi-audio{{cite web |url=https://developer.apple.com/documentation/uniformtypeidentifiers/uttype/3551530-midi |title=midi |work=Apple Developer Documentation: Uniform Type Identifiers |publisher=Apple Inc |access-date=22 May 2023 |archive-date=22 May 2023 |archive-url=https://web.archive.org/web/20230522155319/https://developer.apple.com/documentation/uniformtypeidentifiers/uttype/3551530-midi |url-status=live }}
| conforms_to            = public.audio
| magic                  = {{code|4D 54 68 64}} ("MThd" in ASCII; appears at the start of a MIDI file)
| max_size               = No strict limit; practical limits depend on hardware/software handling the file.
| owner                  = MIDI Manufacturers Association (MMA), International MIDI Association (IMA)
| type                   = Musical performance data (not actual audio)
| compression            = Uncompressed (but can be embedded in compressed archives)
| released               = 1990
| genre                  = Musical notation
| latest_release_version = MIDI 2.0
| latest_release_date    = 2020
| container_for          = MIDI data (notes, controllers, tempo, instrument changes)
| contained_by           = RIFF, Standard MIDI File
| extended_from          = Original MIDI 1.0 protocol
| extended_to            = MIDI 2.0 (adds higher resolution and two-way communication)
| standard               = MIDI Manufacturers Association (MMA) specifications
| open                   = Yes
| standards              = MIDI 1.0, MIDI 2.0 (since 2020)
| free                   = Yes
| url                    = [https://midi.org/standard-midi-files-specification https://midi.org/standard-midi-files-specification]
}}

The '''Standard MIDI File''' ('''SMF''') is a [[file format]] that provides a standardized way for music sequences to be saved, transported, and opened in other systems. The standard was developed and is maintained by the MMA, and usually uses a <code>.mid</code> extension.<ref>{{cite web|url=https://www.midi.org/specifications-old/item/standard-midi-files-smf|title=Standard MIDI Files (SMF) Specification|website=www.midi.org|access-date=23 October 2019|archive-date=23 October 2019|archive-url=https://web.archive.org/web/20191023033822/https://www.midi.org/specifications-old/item/standard-midi-files-smf|url-status=dead}}</ref> The compact size of these files led to their widespread use in computers, mobile phone [[ringtone]]s, webpage authoring and musical greeting cards. These files are intended for universal use and include such information as note values, timing and track names. Lyrics may be included as [[metadata]], and can be displayed by [[karaoke]] machines.<ref>Hass, Jeffrey. "[http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI10.shtml Chapter Three: How MIDI works 10] {{webarchive|url=https://web.archive.org/web/20150607074023/http://www.indiana.edu/%7Eemusic/etext/MIDI/chapter3_MIDI10.shtml |date=7 June 2015 }}". Indiana University Jacobs School of Music. 2010. Web 13 August 2012</ref>

SMFs are created as an export format of software sequencers or hardware workstations. They organize MIDI messages into one or more parallel [[Multitrack recording|tracks]] and time-stamp the events so that they can be played back in sequence. A [[Header (computing)|header]] contains the arrangement's track count, tempo and an indicator of which of three SMF formats the file uses. A type 0 file contains the entire performance, merged onto a single track, while type 1 files may contain any number of tracks that are performed synchronously. Type 2 files are rarely used<ref>{{cite web |url=http://www.midi.org/aboutmidi/tut_midifiles.php |title=MIDI Files |archive-url=https://web.archive.org/web/20120822132443/http://www.midi.org/aboutmidi/tut_midifiles.php |archive-date=22 August 2012 |website=midi.org |publisher=Music Manufacturers Association |quote=a Type 2 was also specified originally but never really caught on}}</ref> and store multiple arrangements, with each arrangement having its own track and intended to be played in sequence.

=====RMID files=====
[[Microsoft Windows]] bundles SMFs together with [[Downloadable Sounds]] (DLS) in a [[Resource Interchange File Format]] (RIFF) wrapper, as '''RMID files''' with a <code>.rmi</code> extension. RIFF-RMID has been [[deprecated]] in favor of '''Extensible Music Files''' ([[XMF]]).<ref>"[http://www.digitalpreservation.gov/formats/fdd/fdd000120.shtml RIFF-based MIDI File Format] {{webarchive|url=https://web.archive.org/web/20120817183246/http://www.digitalpreservation.gov/formats/fdd/fdd000120.shtml |date=17 August 2012 }}". ''digitalpreservation.gov''. Library of Congress. 26 March 2012. Web. 18 August 2012</ref>

=====Software=====
{{Main|Comparison of MIDI editors and sequencers}}

The main advantage of the personal computer in a MIDI system is that it can serve a number of different purposes, depending on the software that is loaded.<ref name="Huber 1991" />{{rp|55|date=November 2012}} [[Computer multitasking|Multitasking]] allows simultaneous operation of programs that may be able to share data with each other.<ref name="Huber 1991" />{{rp|65|date=November 2012}}

=====Sequencers=====
{{Main|Music sequencer}}
{{See also|Audio sequencer|Digital audio workstation}}

Sequencing software can be used to manipulate recorded MIDI data with standard computer editing features such as [[cut, copy and paste]] and [[drag and drop]]. [[Keyboard shortcut]]s can be used to streamline workflow, and, in some systems, editing functions may be invoked by MIDI events. The sequencer can set each channel to play a different sound and gives a graphical overview of the arrangement. A variety of editing tools are made available, including a notation display or [[scorewriter]] that can be used to create printed parts for musicians. Tools such as [[Loop (music)|looping]], [[quantization (music)|quantization]], randomization, and [[transposition (music)|transposition]] simplify the arranging process.

[[Beat (music)|Beat]] creation is simplified, and [[groove (music)|groove]] templates can be used to duplicate another track's rhythmic feel. Realistic expression can be added through the manipulation of real-time controllers. Mixing can be performed, and MIDI can be synchronized with recorded audio and video tracks. Work can be saved, and transported between different computers or studios.<ref>Gellerman, Elizabeth. "Audio Editing SW Is Music to Multimedia Developers' Ears". ''Technical Horizons in Education Journal''. Vol. 22, No. 2. Sep 1994</ref><ref name="Desmond">Desmond, Peter. "ICT in the Secondary Music Curriculum". ''Aspects of Teaching Secondary Music: Perspectives on Practice''. ed. Gary Spruce. New York: RoutledgeFalmer, 2002</ref>{{rp|164–6|date=November 2012}}

Sequencers may take alternate forms, such as drum pattern editors that users can use to create beats by clicking on pattern grids,<ref name="Huber 1991" />{{rp|118|date=November 2012}} and loop sequencers such as [[ACID Pro]], which combine MIDI with prerecorded audio loops whose tempos and keys are matched to each other. Cue-list sequencing is used to trigger dialogue, sound effect, and music cues in stage and broadcast production.<ref name="Huber 1991" />{{rp|121|date=November 2012}}

=====Notation software=====
{{Main|Scorewriter}}
With MIDI, notes played on a keyboard can automatically be transcribed to [[sheet music]].<ref name="Holmes3" />{{rp|213|date=November 2012}} [[Scorewriter|Scorewriting]] software typically lacks advanced sequencing tools and is optimized for the creation of a neat, professional printout designed for live instrumentalists.<ref name="Desmond" />{{rp|157|date=November 2012}} These programs provide support for dynamics and expression markings, chord and lyric display, and complex score styles.<ref name="Desmond" />{{rp|167|date=November 2012}} Software is available that can print scores in [[braille]].<ref>Solomon, Karen. "[https://www.wired.com/culture/lifestyle/news/2000/02/34495 You Gotta Feel the Music] {{webarchive|url=https://web.archive.org/web/20090816175359/http://www.wired.com/culture/lifestyle/news/2000/02/34495 |date=16 August 2009 }}". ''wired.com''. Condé Nast. 27 February 2000. Web. 13 August 2012.</ref>

Notation programs include [[Finale (software)|Finale]], [[Encore (software)|Encore]], [[Sibelius (software)|Sibelius]], [[MuseScore]] and [[Dorico]]. [[SmartScore]] software can produce MIDI files from [[Image scanner|scanned]] sheet music.<ref>Cook, Janet Harniman. "[http://www.soundonsound.com/sos/dec98/articles/midiscan.265.htm Musitek Midiscan v2.51] {{webarchive|url=https://web.archive.org/web/20120110074408/http://www.soundonsound.com/sos/dec98/articles/midiscan.265.htm |date=10 January 2012 }}". ''Sound on Sound''. SOS Publications. Dec 1998. Print.</ref>

=====Editors and librarians=====
Users can program their equipment through the path editor as a computer interface. These became essential with the appearance of complex synthesizers such as the [[Yamaha FS1R]],<ref>{{cite magazine |last=Johnson |first=Derek |url=http://www.soundonsound.com/sos/mar99/articles/yamahafs1r.htm |title=Yamaha FS1R Editor Software |archive-url=https://web.archive.org/web/20111225133744/http://www.soundonsound.com/sos/mar99/articles/yamahafs1r.htm |archive-date=25 December 2011 |magazine=Sound on Sound |date=March 1999}}</ref> which contained several thousand programmable parameters, but had an interface that consisted of fifteen tiny buttons, four knobs and a small LCD.<ref>{{cite magazine |last1=Johnson |first1=Derek |first2=Debbie |last2=Poyser |url=http://www.soundonsound.com/sos/dec98/articles/yamfs1r.549.htm |title=Yamaha FS1R |archive-url=https://web.archive.org/web/20070415184804/http://www.soundonsound.com/sos/dec98/articles/yamfs1r.549.htm |archive-date=15 April 2007 |magazine=Sound on Sound |date=December 1998}}</ref> Digital instruments typically discourage users from experimentation, due to their lack of the feedback and direct control that switches and knobs would provide,<ref name="Gibbs" />{{rp|393|date=November 2012}} but patch editors give owners of hardware instruments and effects devices the same editing functionality that is available to users of software synthesizers.<ref>{{cite web |url=http://www.squest.com/Products/MidiQuest11/index.html |title=Sound Quest MIDI Quest 11 Universal Editor |archive-url=https://web.archive.org/web/20140306223334/http://www.squest.com/Products/MidiQuest11/index.html |archive-date=6 March 2014 |website=squest.com}}</ref> Some editors are designed for a specific instrument or effects device, while other, ''universal'' editors support a variety of equipment, and ideally can control the parameters of every device in a setup through the use of System Exclusive messages.<ref name="Huber 1991"/>{{rp|129|date=November 2012}} System Exclusive messages use the MIDI protocol to send information about the synthesizer's parameters.

Patch librarians have the specialized function of organizing the sounds in a collection of equipment and exchanging entire banks of sounds between an instrument and a computer. In this way the device's limited patch storage is augmented by a computer's much greater disk capacity.<ref name="Huber 1991"/>{{rp|133|date=November 2012}} Once transferred to the computer, custom patches can be shared with other owners of the same instrument.<ref name="Cakewalk">{{cite web |url=http://www.cakewalk.com/support/kb/reader.aspx/2007013074 |title=Desktop Music Handbook&nbsp;– MIDI |archive-url=https://web.archive.org/web/20120814222211/http://www.cakewalk.com/Support/kb/reader.aspx/2007013074 |archive-date=14 August 2012 |website=cakewalk.com |publisher=Cakewalk, Inc. |date=26 November 2010}}</ref> Universal editor/librarians that combine the two functions were once common, and included Opcode Systems' Galaxy, [[Emagic|eMagic]]'s SoundDiver, and MOTU's Unisyn. Although these older programs have been largely abandoned with the trend toward computer-based synthesis using virtual instruments, several editor/librarians remain available, including Coffeeshopped Patch Base,<ref>{{cite web | url=https://coffeeshopped.com/patch-base | title=Patch Base | access-date=7 September 2022 | archive-date=7 September 2022 | archive-url=https://web.archive.org/web/20220907055311/https://coffeeshopped.com/patch-base | url-status=live }}</ref> Sound Quest's Midi Quest, and several editors from Sound Tower. [[Native Instruments]]' Kore was an effort to bring the editor/librarian concept into the age of software instruments,<ref>{{cite web |first=Simon |last=Price |url=http://www.soundonsound.com/sos/jul06/articles/nikore.htm |title=Native Instruments Kore |publisher=Sound on Sound |date=July 2006 |website=Soundonsound.com |access-date=27 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20130602131027/http://www.soundonsound.com/sos/jul06/articles/nikore.htm |archive-date=2 June 2013}}</ref> but was abandoned in 2011.<ref>{{Cite web|url=https://www.musicradar.com/news/tech/native-instruments-discontinues-kore-457945|title=Native Instruments discontinues Kore|author1=Ben Rogerson|date=7 June 2011|website=MusicRadar|access-date=7 September 2022|archive-date=7 September 2022|archive-url=https://web.archive.org/web/20220907055313/https://www.musicradar.com/news/tech/native-instruments-discontinues-kore-457945|url-status=live}}</ref>

=====Auto-accompaniment programs=====
Programs that can dynamically generate accompaniment tracks are called ''auto-accompaniment'' programs. These create a full-band arrangement in a style that the user selects and sends the result to a MIDI sound-generating device for playback. The generated tracks can be used as educational or practice tools, as accompaniment for live performances, or as a songwriting aid.<ref name="Bozeman" />{{rp|42|date=November 2012}}

=====Synthesis and sampling=====
{{Main|Software synthesizer|Software sampler}}
Computers can use software to generate sounds, which are then passed through a [[digital-to-analog converter]] (DAC) to a power amplifier and loudspeaker system.<ref name="Holmes3" />{{rp|213|date=November 2012}} The number of sounds that can be played simultaneously (the [[polyphony]]) is dependent on the power of the computer's [[CPU]], as are the [[sample rate]] and [[Audio bit depth|bit depth]] of playback, which directly affect the quality of the sound.<ref>{{cite magazine |last=Lehrman |first=Paul D. |url=http://www.soundonsound.com/sos/1995_articles/oct95/softwaresynthesis.html |title=Software Synthesis: The Wave Of The Future? |archive-url=https://web.archive.org/web/20120110172147/http://www.soundonsound.com/sos/1995_articles/oct95/softwaresynthesis.html |archive-date=10 January 2012  |magazine=Sound on Sound |publisher=SOS Publications |date=October 1995}}</ref> Synthesizers implemented in software are subject to timing issues that are not necessarily present with hardware instruments, whose dedicated operating systems are not subject to interruption from background tasks as desktop [[operating system]]s are. These timing issues can cause synchronization problems, and clicks and pops when sample playback is interrupted. Software synthesizers also may exhibit additional [[latency (audio)|latency]] in their sound generation.<ref name="WalkerTime">{{cite magazine |last=Walker |first=Martin |url=https://www.soundonsound.com/techniques/identifying-solving-pc-midi-audio-timing-problems |title=Identifying & Solving PC MIDI & Audio Timing Problems |archive-url=https://web.archive.org/web/20120110151234/http://www.soundonsound.com/sos/mar01/articles/pcmusician.asp |archive-date=10 January 2012 |magazine=Sound on Sound |publisher=SOS Publications |date=March 2001 |url-status=live}}</ref>

The roots of software synthesis go back as far as the 1950s, when [[Max Mathews]] of [[Bell Labs]] wrote the [[MUSIC-N]] programming language, which was capable of non-real-time sound generation.<ref name="DMM1997">{{cite magazine |last=Miller |first=Dennis |url=http://www.soundonsound.com/sos/1997_articles/may97/softwaresynth2.html |title=Sound Synthesis On A Computer, Part 2 |archive-url=https://web.archive.org/web/20120110201713/http://www.soundonsound.com/sos/1997_articles/may97/softwaresynth2.html |archive-date=10 January 2012 |magazine=Sound on Sound |publisher=SOS Publications |date=May 1997}}</ref> Reality, by Dave Smith's [[Seer Systems]] was an early synthesizer that ran directly on a host computer's CPU. Reality achieved a low latency through tight driver integration, and therefore could run only on [[Creative Labs]] soundcards.<ref>{{cite web |url=http://www.keyboardmag.com/article/Midi-Ancestors-and-Milestones/2171 |title=MIDI Ancestors and Milestones |archive-url=https://web.archive.org/web/20121030112748/http://www.keyboardmag.com/article/Midi-Ancestors-and-Milestones/2171 |archive-date=30 October 2012 |publisher=[[New Bay Media]]}}</ref><ref>{{cite magazine |last=Walker |first=Martin |url=http://www.soundonsound.com/sos/1997_articles/nov97/seerreality.html |title=Reality PC |archive-url=https://web.archive.org/web/20150225043325/http://www.soundonsound.com/sos/1997_articles/nov97/seerreality.html |archive-date=25 February 2015 |magazine=Sound on Sound |publisher=SOS Publications |date=November 1997}}</ref> Syntauri Corporation's Alpha Syntauri was another early software-based synthesizer. It ran on the Apple IIe computer and used a combination of software and the computer's hardware to produce additive synthesis.<ref>{{cite web | url=https://www.vintagesynth.com/misc/alphasyntauri.php | title=Syntauri alphaSyntauri &#124; Vintage Synth Explorer | access-date=7 September 2022 | archive-date=7 September 2022 | archive-url=https://web.archive.org/web/20220907060813/https://www.vintagesynth.com/misc/alphasyntauri.php | url-status=live }}</ref> Some systems use dedicated hardware to reduce the load on the host CPU, as with [[Symbolic Sound Corporation]]'s Kyma System,<ref name="DMM1997" /> and the [[Creamware (company)|Creamware]]/[[Sonic Core]] Pulsar/SCOPE systems,<ref>{{cite magazine |last=Wherry |first=Mark |url=http://www.soundonsound.com/sos/jun03/articles/creamwarescope.asp |title=Creamware SCOPE |archive-url=https://web.archive.org/web/20111225043650/http://www.soundonsound.com/sos/jun03/articles/creamwarescope.asp |archive-date=25 December 2011 |magazine=Sound on Sound |publisher=SOS Publications |date=June 2003}}</ref> which power an entire recording studio's worth of instruments, [[effect unit]]s, and [[audio console|mixer]]s.<ref>{{cite web |last=Anderton |first=Craig |url=http://www.keyboardmag.com/article/sonic-core-scope-xite-1/147874 |title=Sonic Core SCOPE Xite-1 |archive-url=https://web.archive.org/web/20121030112726/http://www.keyboardmag.com/article/sonic-core-scope-xite-1/147874 |archive-date=30 October 2012 |publisher=[[New Bay Media]]}}</ref> The ability to construct full MIDI arrangements entirely in computer software allows a composer to render a finalized result directly as an audio file.<ref name="Why" />

=====Game music=====
Early PC games were distributed on floppy disks, and the small size of MIDI files made them a viable means of providing soundtracks. Games of the [[DOS]] and early Windows eras typically required compatibility with either [[Ad Lib, Inc.|Ad Lib]] or [[Sound Blaster]] audio cards. These cards used [[FM synthesis]], which generates sound through [[modulation]] of [[sine wave]]s. [[John Chowning]], the technique's pioneer, theorized that the technology would be capable of accurate recreation of any sound if [[Additive synthesis|enough sine waves were used]], but budget computer audio cards performed FM synthesis with only two sine waves. Combined with the cards' 8-bit audio, this resulted in a sound described as "artificial"<ref>David Nicholson. "[http://www.highbeam.com/doc/1P2-946733.html HARDWARE]."{{webarchive|url=https://web.archive.org/web/20130502120852/http://www.highbeam.com/doc/1P2-946733.html |date=2 May 2013 }} The Washington Post. 1993.</ref> and "primitive".<ref name="Levy">Levy, David S. "[http://www.highbeam.com/doc/1G1-14803399.html Aztech's WavePower daughtercard improves FM reception. (Aztech Labs Inc.'s wavetable synthesis add-on card for Sound Blaster 16 or Sound Galaxy Pro 16 sound cards) (Hardware Review) (Evaluation).] {{webarchive|url=https://web.archive.org/web/20130502121538/http://www.highbeam.com/doc/1G1-14803399.html |date=2 May 2013 }}" Computer Shopper. SX2 Media Labs LLC. 1994.</ref>

Wavetable [[daughterboard]]s that were later available provided audio samples that could be used in place of the FM sound. These were expensive, but often used the sounds from respected MIDI instruments such as the [[E-mu Proteus]].<ref name="Levy" /> The computer industry moved in the mid-1990s toward wavetable-based soundcards with 16-bit playback but standardized on a 2&nbsp;MB of wavetable storage, a space too small in which to fit good-quality samples of 128 General MIDI instruments plus drum kits. To make the most of the limited space, some manufacturers stored 12-bit samples and expanded those to 16 bits on playback.<ref>Labriola, Don. "[http://www.highbeam.com/doc/1G1-16232686.html MIDI masters: wavetable synthesis brings sonic realism to inexpensive sound cards. (review of eight Musical Instrument Digital Interface sound cards) (includes related articles about testing methodology, pitfalls of wavetable technology, future wavetable developments) (Hardware Review) (Evaluation).]"{{webarchive|url=https://web.archive.org/web/20130502104559/http://www.highbeam.com/doc/1G1-16232686.html |date=2 May 2013 }} Computer Shopper. SX2 Media Labs LLC. 1994.</ref>