Editing Pro Tools (section)

=== Digidesign Sound Tools and Sound Designer II software (1989–1990) ===
The combination of the hardware and the software was called Sound Tools. Advertised as the "first tapeless studio",{{sfn|Milner|2009|p=245}} it was presented on January 20, 1989, at the [[NAMM Show|NAMM International Music & Sound Expo]]. The system relied on a [[NuBus]] card called Sound Accelerator, equipped with one [[Motorola 56000|Motorola 56001]] processor. The card provided 16-bit playback and 44.1/48&nbsp;kHz recording through a two-channel [[Analog-to-digital converter|A/D converter]] (AD In), while the DSP handled signal processing, which included a ten-band [[graphic equalizer]], a [[parametric equalizer]], [[Audio time stretching and pitch scaling|time stretching]] with pitch preservation, fade-in/fade-out envelopes, and crossfades ("merging") between two sound files.{{sfn|Manning|2013|p=387}}<ref>{{Cite journal |last=Lehrman |first=Paul D. |date=August 1989 |title=Digidesign Sound Tools |url=http://www.muzines.co.uk/articles/digidesign-sound-tools/5626 |journal=[[Sound on Sound]] |volume=46 |pages=60–63 |via=Muzines}}</ref>

Sound Tools was bundled with Sound Designer II software, which was, at this time, a simple mono or stereo audio editor running on [[Macintosh SE|Mac SE]] or [[Macintosh II|Mac II]]; digital audio acquisition from [[Digital Audio Tape|DAT]] was also possible.<ref>{{Cite journal |last=Mellor |first=David |date=November 1991 |title=Hands on: Sound Tools |url=http://www.muzines.co.uk/articles/hands-on/7527 |journal=[[Sound on Sound]] |volume=73 |pages=70–74 |via=Muzines}}</ref> A two-channel digital interface (DAT-I/O) with [[AES/EBU]] and [[S/PDIF]] connections was made available later in 1989, while the Pro I/O interface came out in 1990 with 18-bit converters.{{sfn|Collins|2002|p=9}}

The file format used by Sound Designer II (SDII) became eventually a standard for digital audio file exchange until the [[WAV]] file format took over a decade later. Since audio streaming and [[non-destructive editing]] were performed on hard drives, the software was still limited by their performance; densely edited tracks could cause glitches.<ref>{{cite web|url=http://www.namm.org/library/oral-history/evan-brooks|title=NAMM Library: Oral History|last=Brooks|first=Evan|date=2007-01-20|work=NAMM.org|access-date=20 June 2015}}</ref> However, the rapidly evolving computer technology allowed developments towards a multi-track sequencer.