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Sierra On-Line Interpreter Patch
Developer: Sierra On-Line
Header: Unknown
Content: Instrument
Instruments: Intrinsic
Target Output
Output - Digital Audio - No.png Output - MIDI.png Output - FM Synthesis.png Output - PSG.png
Released: 1988-??-??
First Game: King's Quest IV: The Perils of Rosella (DOS)
  • *.*

The Sierra On-Line Interpreter Patch format was created by Sierra On-Line for their games that used their SCI engine. Patch files contain special instrument definitions that must be sent to the audio device before playing an SCI music file. If the patch isn't sent, the song will still play the correct notes, but with incorrect instruments.

All of the audio devices supported by the SCI format require a patch file except for the PC Speaker, Tandy 3 Voice, PS-1 Audio, and General MIDI. The reason these devices do not require a patch is because they cannot have customized instruments.

Patch files can contain multiple system exclusive definitions in each file. For example, the MT-32 patch has 2 definitions. The first contains the instrument definitions and is sent when the game loads, the second sets the instruments back to the factory default when the game closes.

Patch files are always named "patch" and have a numeric extension to signify which device they're for. You can see the index below.

Patch File Supported Devices
patch.000 D-110, D-10, D-20
patch.001 LAPC-I, MT-32, MT-100, CM-32L, CM-64
patch.002 FB-01, PC Music Feature
patch.003 AdLib, Sound Blaster, Pro AudioSpectrum
patch.004 CT-460, MT-540
patch.007 CSM-1
patch.101 Creative Music System, Game Blaster


  • SV - Windows



All of Sierra's SCI games use the SCI Patch format.

Released Title Sample
1988-??-?? King's Quest IV: The Perils of Rosella (DOS)
1989-??-?? Code-Name: Iceman (DOS)
1991-??-?? Castle of Dr. Brain (DOS)
1993-??-?? Space Quest V: The Next Mutation (DOS)

Hot to Obtain

PATCH files must be extracted from compressed Sierra resource files. There are various programs in the links section below that can accomplish this.