If I recall, the original depiction of a TM was as some kind of belt-like device. I forget the details of it, but it seems the idea of it being some kind of device that somehow imparts the knowledge of how to use a certain move to the pokemon stuck. It's an interesting piece of science fiction, but it makes me wonder if such a thing exists for humans, and if not, then why not. Apparently it doesn't since information is still presented in the same manner as it is in real life. Seems like a horrible inconsistency. Anyway, it's presented as a CD one part as it became the popular medium at the time, and I suppose as a means to imply that we're using the same device, it's just that we change the information being presented, encoded on the disks. The device by itself has never been portrayed again, though, just the disks. Any of the handheld devices that are the required equipment of a trainer have been used as the device that uses the disks. I have no preference personally because I do not think of such things. In reality, I assume moves to be trained the old fashioned way.
