Editing MIDI (section)

===Instruments===
[[File:Korg 05RW front.jpg|thumb|alt=A General MIDI sound module.|A [[sound module]], which requires an external controller (e.g., a MIDI keyboard) to trigger its sounds. These devices are highly portable, but their limited programming interface requires computer-based tools for comfortable access to their sound parameters.]]

A MIDI instrument contains ports to send and receive MIDI signals, a CPU to process those signals, an interface for user programming, audio circuitry to generate sound, and controllers. The operating system and factory sounds are often stored in a [[read-only memory]] (ROM) unit.<ref name="Huber 1991" />{{rp|67–70|date=November 2012}}

A MIDI instrument can also be a stand-alone module (without a piano-style keyboard) consisting of a General MIDI soundboard (GM, GS and XG), onboard editing, including transposing, MIDI instrument selection and adjusting volume, pan, reverb levels and other MIDI controllers. Typically, the MIDI module includes a screen, so the user can view information for the currently selected function.

====Synthesizers====
Synthesizers may employ any of a variety of sound generation techniques. They may include an integrated keyboard or may exist as sound modules that generate sounds when triggered by an external controller, such as a MIDI keyboard. Sound modules are typically designed to be mounted in a [[19-inch rack]].<ref name="Huber 1991" />{{rp|70–72|date=November 2012}} Manufacturers commonly produce a synthesizer in both standalone and rack-mounted versions, and often offer the keyboard version in a variety of sizes.

====Samplers====
A [[sampler (musical instrument)|sampler]] can record and digitize audio, store it in [[random-access memory]] (RAM), and play it back. With a sampler, users typically can edit a [[Sampling (signal processing)|sample]] and save it to a hard disk, apply effects to it, and shape it with the same tools that [[subtractive synthesizer]]s use. They also may be available in either keyboard or rack-mounted form.<ref name="Huber 1991" />{{rp|74–8|date=November 2012}} Instruments that generate sounds through sample playback, but have no recording capabilities, are known as "[[Rompler|ROMplers]]".

Samplers did not become established as viable MIDI instruments as quickly as synthesizers did due to the expense of memory and processing power at the time.<ref name="Manning3" />{{rp|295|date=November 2012}} The first low-cost MIDI sampler was the [[Ensoniq Mirage]], introduced in 1984.<ref name="Manning3" />{{rp|304|date=November 2012}} MIDI samplers are typically limited by displays that are too small to use to edit sampled waveforms, although some can be connected to a computer monitor.<ref name="Manning3" />{{rp|305|date=November 2012}}

====Drum machines====
[[Drum machine]]s typically are sample playback devices that specialize in drum and percussion sounds. They commonly contain a sequencer for creating drum patterns and arranging them into a song. There often are multiple audio outputs so that each sound or group of sounds can be routed to a separate output. The individual drum voices may be playable from another MIDI instrument or from a sequencer.<ref name="Huber 1991" />{{rp|84|date=November 2012}}

====Workstations and hardware sequencers====
{{Further|Music workstation|Music sequencer}}
[[File:Tenori-on.jpg|thumb|alt=A button matrix MIDI controller|Yamaha's [[Tenori-on]] controller allows arrangements to be built by "drawing" on its array of lighted buttons. The resulting arrangements can be played back using its internal sounds or external sound sources, or recorded in a computer-based sequencer.]]

Sequencer technology predates MIDI. [[Analog sequencer]]s use [[CV/Gate]] signals to control pre-MIDI analog synthesizers. MIDI sequencers typically are operated by transport features modeled after those of [[tape deck]]s. They are capable of recording MIDI performances and arranging them into individual tracks using a [[multitrack recording]] paradigm. Music workstations combine controller keyboards with an internal sound generator and a sequencer. These can be used to build complete arrangements and play them back using their own internal sounds and function as self-contained music production studios. They commonly include file storage and transfer capabilities.<ref name="Huber 1991" />{{rp|103–4|date=November 2012}}