In Windows 3.1 MIDI Mapper, what is the difference between the patch and key maps?
Patch maps are used to remap MIDI Program Change messages. For example, maybe a MIDI file assumes that the Grand Piano patch is #1 on your module. But maybe your module has an Oboe patch for #1 instead. Maybe the Grand Piano patch is #40 on your module. So when the MIDI file tells your module to change to Grand Piano, it will accidentally misinterpret this as a command to play the Oboe. You can use MIDI Mapper to fix this. Set MIDI Mapper’s patch #1 to send a Program Change value of 40 instead. Now when the MIDI file sends a Program Change for patch #1, MIDI Mapper instead sends a Program Change for patch #40, and your module does in fact play that Grand Piano. Most MIDI files nowadays expect a General MIDI patch set (ie, certain instruments in a certain order). If your module is not General MIDI, then you should use MIDI Mapper to remap a GM patch set to your module’s patch numbers. Key maps are used to remap MIDI Note messages. Usually, every different note number of a Drum Kit plays
