This is a simple 16-step MIDI sequencer written in BASIC for the Commodore VIC-20. It is using the VIC-20 MIDI cartridge from RETRO Innovations.
There is a short demo video over on YouTube
Copy the file vicseq.prg
over to your favorite device to get data onto the VIC-20, eg. SD2IEC or Pi1541 floppy disk drive emulator. A memory expansion needs to be in place in order for the program to run.
Start it with the following commands:
LOAD"VICSEQ.PRG",8
RUN
Replace the device number accordingly.
http://www.go4retro.com/products/vicmidi
https://github.com/LeifBloomquist/VICMIDI
https://worldradiohistory.com/UK/Mapelin/Maplin-Project-Book-22.pdf#page=32