From reading the driver documentation on GitHub, which you can find at https://github.com/mamedev/mame/blob/ma … ectalk.cpp if one is interested, it seems that this driver was around for a long time. From what I could tell, I'm guessing the machine wasn't well emulated, and it was probably within MESS before it merged with MAME a few years later (don't know when as I haven't been keeping up with MAME as of recently).
I have tested it, and from what I could gather, the sample rate of the sound emulation is a bit too high, no doubt because MAME is running at either 44100 or 48000 kHz.
Also worth noting is that the machine takes over your entire keyboard, meaning that the Escape key won't work either. The only way I've found to exit it is to end MAME through Task Manager. Another thing worth noting is that you can't copy full songs into it. As far as I am aware, the machine will only accept a limited amount of entered characters at a time. Of course, you can't copy paste stuff into it, obviously.
Hello. He-he-he-he-have some respect and don't spoil the game. It's impossible to have mysteries nowadays, because of nosy people like you. Please keep all of this between us. If you post it online, I won't make any more secrets. No one will be impressed. It will be your fault! He-he-he-he-ha-he-he-ha-he-he.
- abc_123_a.ogg, Undertale v1.000 -