Abstract This article documents the hardware and software mods to provide 2 extra (4 total) Midi I/O ports on the MB SEQ4L. The added ports use the onboard UARTs (2,3) of the LPC MIOS32 core. The underlying sequencer code supports these ports (MIDI 3 and 4), but in the case of MIDI 3, the pins used, need to be replaced as they are( were) used to drive LED matrix columns. I chose J28 to provide these LED column driver pins, unfortunately they are part of the CV output (which I don't want) whi