via this auction
"Official description of the Simmons SDS9: The SDS9 is a 5-drum kit, comprising bass, snare and 3 tom-toms, triggering up to 40 complete “drum kits” (20 factory and 20 programmable presets).
Hitting a specific pad (not included)triggers the corresponding channel on the ‘electronics’. A microprocessor controls the dynamic (or volume) of each individual ‘hit’ giving a sensitivity to playing previously unheard of in electronic drums: a ‘real’ drum feel, in fact!
The Simmons SDS9 gives you the sounds, feel and control of acoustic drums plus all the sounds and advantages of electronic drums. (Editor's Note: Well, that might be stretching it a bit, but it was written in the 1980's :)
The SDS9 electronically synthesises the sounds of each drum. The bass, snare and toms use different methods of synthesis – each the most appropriate for the sound and control you require. The bass is software generated directly by the computer. The snare/rim are digital samples of acoustic drums. The tom-toms are synthesised using analogue circuitry. The tom also have unique ‘second skin’ switch to match the sound and response of a double headed acoustic tom.
The program/store memory facility allows you to build up your own drum sounds. These programmed sounds can be saved to tape, giving you almost limitless capacity to store new sounds, or recall previously stored sounds.
There is also a sophisticated automatic trigger that allows sounds to be reviewed without hitting the pads, and a mode where the drums can be triggered by button tapping.
The SDS9 is the first drum kit that has a built in MIDI interface. This is completely assignable in terms of voice changes and note values. By using the MIDI interface you can directly interface with many available keyboard synthesisers and play their voices from the pads. You can also use MIDI real time recorders/sequencers to record your playing and then playback the SDS9 exactly as you played it.
Another interesting feature of the SDS9 is its built in programmable echo. This programmable effect can be used for single slap-back echo or for long repeating echoes to produce stunningly unique rhythmic-ic-ic patterns and eff-eff-ects-ects.
We have done a lot of work using the latest high technology and computer aided design tools to develop the SDS9 – a new instrument, using new voicing techniques and new materials to give you everything any acoustic kit has to offer and much more besides – the kit that’s destined to add a whole new dimension to your art."
"They produce the bass drum and three tom sounds with 3 CURTIS ELECTRO MUSIC (CEM) chips. At the time of this writing, ONE of these rare chips is on sale on Ebay for over $50. That means there just 3 of the myriad of chips in this unit are worth $150 or more.
But this thing is a true HYBRID combining the best of both ANALOG and DIGITAL. There are three EPROM sockets which allow chips (that are still available) to be used as sound sources - digitally recorded sound sources. In the case with the chips included with this machine, SNARE and TWO RIM sounds - which can easily be transmuted into cowbells and all sorts of clangourous anomolies.
PLUS this thing is PROGRAMMABLE, and can RUN on it's OWN as a DRUM MACHINE (although it is widely known as a brain for a set, where you hook up your triggers to it. Triggers can be from drum pads, or what have you. Anything you can attach a trigger to.
AND it has a TAPPABLE feature, so it's all inclusive if you want it to take up less real estate.
The MATRIX-STYLE setup yields an exceptionally wide range of control with a minimum of controls. You can do a lot more with the sounds, and with it as a SELF-PROPELLED DRUM MACHINE than it first appears.
TAKE A LOOK..... the functions listed are varied by the potentiometers to the left, when you've selected the ONE of the SIX SOUND MODULES, as confirmed by the PROG light above that channel.
USING external triggers, you plug them into the phone jacks on the top/back panel, set up sensitivity individually, and then select one of 5 positions on the KIT control, each of which has 4 memories, for a total of 20 programmable complete kits. MIDI is fully implemented, and I believe this was the first drum machine to implement MIDI. All the LED's operate and the lower left hand programming controls all work. I'm not sure if the filter sweep and tone pitch controls work as they should, although these parameters do vary between the presets and kits. There is also a bit of a nasty nick there between channel 2 and 3, but this doesn't affect operation.
There are INDIVIDUAL MODULE OUTPUTS and MIXED OUTPUT, as well as HEADPHONE OUTPUT."