I bought a Digisette Duo-MP3 from eBay. It has 32 MB of on-board flash RAM. Experimentation demonstrated that the player will handle monophonic, variable bit-rate recordings and output "acceptable" fidelity at 56 kilobits per second yielding over an hour of play time. The player supports mechanically-actuated forward, reverse, stop, volume-up, and volume-down buttons. These buttons appear to be able to be emulated using solid-state hardware and wired into the circuitry of the player without difficulty.