SEQ541 is a free MIDI pattern sequencer for OS X.
The program is designed to be extremely flexible, all it requires is that you have an external MIDI device generating a clock and it will output notes in time to a pattern sequence you specify.
- you can’t record patterns, only input them via mouse
- 128-note polyphony
- you can run as many pattern sequencers simultaneously as your CPU can handle
- you can store as many patterns as you want per sequencer
- while playing, transitions to the next pattern don’t occur until the current pattern is done playing
- variable pattern length: 16, 32, 48 and 64 notes
- variable note length: 16th note through whole note in 16th note steps
- fixed note-on velocity 0x64
- play/stop must be driven from an external MIDI source
- MIDI clock must be from an external MIDI source
- can drive any hardware or software MIDI device
- can echo MIDI clock to the external MIDI device (for arpegio or whatever)