I cut my teeth on this hardware sequencer 22 years ago. There was a long break from it in the noughties when I switched to sequencing on a Mac, using Cubase, then Ableton Live. But my development of a technique to synthesize FSK sync signals in Ableton Live and send this as audio to the MC-50's sync-in jacks, has enabled me to slave this hardware to my software with rock-solid timing, giving me the best of both.
(For details see this article on my website).
Why use this old technology today? I've found many reasons, but I suppose they can be generalised as either "speed" or "fun", often both.
Keystroke commands can be so much quicker than using a mouse. They are generated at a lower level of brain architecture, and so have a less disruptive effect on conscious attention, allowing it to focus on the creative effect of the task. Using a mouse engages more parts of the brain, and at a higher level of architecture (e.g. optic cortex needs to track the pointer, and relay this information to the motor cortex controlling the mouse-hand). The result of using keystrokes is a feeling of freedom and flow when creating and editing midi parts. Of course, this assumes you have put the time in to acquire the skills in the first place. The time spent is always repaid well.
Some key commands on the MC-50 make workflow extremely fast:
• [PAUSE] + [RECORD] allows you to start recording (or erasing) from the very tick (one tick is a 96th of a quarter note) that you are stopped at.
• UTILITY 8 (tune) sends an A4 note on all channels when you need to check audio connections or tune your analogue synths.
• [STOP] + [MIDI] sends an All Notes Off message on all channels.
• [PAUSE] + [MIDI] updates all pitchbend and CCs up to that point in the song.
• Hit [LOC] and a number to jump to a Locate point, hit [LOC] + [REC] then a number to set a Locate point right where you are.
For rapid rhythm pattern recording, the MC-50 uses the classic old Roland step-write-while-running style of an 808 or a 909, with eight levels of accent. Its quick and intuitive even just using the 2 line display and the key pad, but it's even better if you are using a midi controller keyboard with a sustain pedal, as this allows instant erase of any particular voice by holding the key down with the pedal depressed, while the pattern loops. I've never seen a faster way of writing/editing rhythms - shame they are only one bar long! But once you write them into the Rhythm Track, you can quickly copy them into a "Phrase" track (a Phrase track is everything else that is not a Rhythm track) to allow sophisticated editing/quantizing that simple pattern writing doesn't allow, so you start simple, then get busy.
There are creative reasons as well. The MC-50, like some other Roland products such as the MC-202 and the TB-303, allow an interesting type of composing whereby you can at first enter, in step time, the notes or chords you want to use, without worrying about their timing position. Then, once they are entered, you can then write, in real time, the velocity/step/gate time of those previously-written notes or chords independently of the actual note values. (Roland call this MODIFY RECORDING). This can get interesting, say, if you send it the midi notes of a groove or a drum machine pattern that you want your sequence to conform to.
Another instant-gratification creative feature are the mute buttons. There are mute buttons for the Rhythm, Tempo, and the eight Phrase tracks. These allow on-the-fly arranging while you are synced to your DAW... Ableton can only beat this for fun if using a fancy, expensive control surface.
Speaking of syncing, there is a widely reported bug in this series of Roland hardware sequencer such as the MC500/MC500mkII/MC50 etc, whereby the unit, when externally synchronized in "loop" or "cycle" mode (the term Roland uses is "Block Repeat"), gets out of time with the sync signal it is being sent. Analyzing this, I have discovered it is because it "loses" a single tick when the loop rolls around again from the end point to the start, causing the timing lag to increase with every cycle. Therefore the bugfix is to specify the loop points, not by bar number, but by LOC (locate) points. This allows you to set the points down to single tick resolution. Place the first LOC point at the 00 point of the first bar, and the end LOC point one tick less than the end of the last bar i.e. at beat 4, tick 95, of the last bar. And so by holding [SHIFT] while hitting [PLAY], loop play will start when the external clock arrives, and continue to play the loop indefinitely, accurately locked to the DAW.
I've written a one page shortcuts guide that I keep near my machine. You can download it here.