The DX100 is a small and portable budget DX synthesizer from Yamaha. Like all DX's it uses (FM) Frequency Modulation synthesis. It's not the easiest form of synthesis to program but can result in some excellent sounds. The DX100 is not as flexible nor powerful as a DX7, but it does have some cool sounds. It is most renowned for its great analog bass sound (Patch #01) that is awesome for techno, house, jungle, and acid music styles; it's very gritty, the bass tone with gristle! However, any other preset sounds that you'll find in the DX100 are pretty bad and require editing for anything else useable.
The DX100 has mini-keys and only 49 of them. No filters, arpeggiators, effects or programmable controllers are available either. Small pitch and mod wheels in the upper left and guitar strap pegs make this synth usable for live use if you're feeling whimsical. If you mess around with the settings on Parameter 13, even if you don't know anything about FM, you can get some seriously twisted sounds out of it. If you're willing to spend a little time with it, it has a lot more potential than just that one bass sound that people will eventually get sick of. And at its currently low street price, it just might be worth getting.