The Simmons Analog Claptrap is a slight further development of the original Musicaid device. The sound synthesis is the same, but it had been extended by a humanizer function which randomly modulated each clap event. The chassis increased slightly, the old-fashioned knobs had been substituted by more modern one.
All in all an inexpensive way to get Simmons analog sounds. But onthe strength of the fact, that this was composed of pretty cheap electronic components, you should not expect the sound of an SDSV or SDS7.
As all desktop devices, the SDS 800 cannot be extended with additional modules.
The SDS 800 has been shipped with 4 Mark IV pads (structurally identical with SDS 9 and SDS 1000 pads) comprising 1 bassdrum pad and 3 small mono pads.