Here’s something I discovered, relating to the behaviour of M1/M2: (mentioned this briefly in the Tracks thread)
M1 and M2 are stored as differences or changes to the default values, not as absolute parameters.
E.g. if you’ve got Grid X-Y set to (20, 30) by default, and you change them to (10, 40) in M1, what’s actually stored in M1 is (-10,+10).
Alright, so what’s the big deal? Well, when used together on the same screen, M1 and M2 add their differences.
Continuing the above example, let’s say that your X-Y for M2 is (30,20), so the stored changes would be (+10,-10).
If you hit either M button, it goes to the corresponding remembered status. But if you press both at once, Grid actually returns to the default values, because (in this example) the M1/2 differences cancel out! Say that M2 X-Y were now (50,50), so its differences would be (+30,+20). Hit both buttons at once, the combined change would be (-10+30,+10+20), so the final X-Y would be (40,60).
I guess this is less of a tip/trick, and more of an exploration into the workings of the OP-1, but I’m sure someone will find this useful. With some clever manipulation, it can effectively be a third memory slot.