via this auction
" The Sequential Model 800 Sequencer is a 256-event cv/gate sequencer based on microprocessor technology. This was probably Sequential's first product. Dave Smith started making these units in his garage. A cv/gate sequencer based on microprocessor technology. First known product from Sequential Circuits. Less than 500 units were produced between 1977 and 1980 starting in Dave Smith's garage.
This is serial number 0330, and was recently refurbished by synth maestro Dave Brown at Modular Synthesis.He did an incredible job, which you can see at this page documenting the repair and restoration
This SCI 800 is described at the bottom of the page (the top of the page is my other, much earlier SCI 800, that truly proved a challenge to reverse engineer and fix!)
It was built like a tank, encased in a 8"X10"X5" metal box. It represents one of the first attempts at a commercial meld between analog and digital technology.
The 800 consists of 16 toggle switches which enable "cells". Each cell can hold up to 16 note-events each. The cells are loaded from CV (control voltage) keyboard via the CV/gate inputs (1 volt per octave) and can be programmed over a 5-octave range. The Gate is switchable between S-trigger and voltage gate. An internal clock runs from 20Hz up to 5kHz to calculate absolute note length or beat division if being driven externally by a low frequency clock. External input is provided via a specially wired plug. A multi-pin parallel connector is used to hook two or more 800's together. A foot-pedal was available for toggling between record and play modes and start/stop. The CV/gate output is quantized to semitones (1/12). The gate can also be switched between S-trigger and voltage gate.
Sequences cannot be stored, however there may have been a battery backup modification. If a hi freq VCO is used to "clock" the sequencer, it can function as a crude audio waveshaper.
The Model 800 can hold up to 256 events. There are 16 switches which enable "cells", which can each contain 16 events. They are loaded by an external CV keyboard and can be programmed over 5 octaves. An internal clock running between 20Hz-5kHz calculates the absolute note length or beat division when driven externally by a low frequency clock.
