My obscure DS music rom search continues, deep cut of the day is this odd unfinished DS port of the Teenage Engineering OP-1!?!?!?
Don't really know what it's quite doing but got some glitch looping + distortion going. There's a screen with a line and in+out points where at some point I briefly got a waveform to appear but not sure how... there's one with concentric circles of switches which just seem to make some click rhythms at a fixed bpm??, the keyboard grid in the photo plays notes, and two nice tape recorders which can record what's going on (including each other) and you can 'scratch' with.
Disappointingly it doesn't seem to record from the mic 
If you hold select and left you can choose which screen is in the top screen
Seems to be no info about it anywhere except this github. Spent a while trying to figure out how to compile it before realising that the included .nds file does actually work on a real DS, just not in my emulator. :-/ https://github.com/efairbanks/op-1
desc from the github page:
This bit of Nintendo DS homebrew is deserving of its own repo. This is specifically pulled from my bitbucket account, and is hopefully the most up-to-date version of this software. It's a digital audio workstation for the Nintendo DS that presents the user with a set of "pages" that represent a particular piece of hardware you might find in a studio. (eg. a reel-to-reel tape recorder, a synthesizer, etc...) It's an ambitious project considering the Nintendo DS's lack of CPU-power, but I'm quite fond of the tape-deck emulation on this thing.
amazing. Gonna try now! thanks for contacting him. I'll share on the Obsolete Music Software group thread unless you want to do so first?
