This video, via Vykaar Tones, is a hands-on demo of the Roland System 100 Model 104 step sequencer.

Note that there are three Model 104’s shown in the video; only the center one is being used in this demo.

Here’s what they have to say about the technical details:

Roland System-100 Model-104 Sequencer sending CV and GATE to a Doepfer Dark Energy Mk1 (out of view) producing the sound, which is also going through eventide delays and reverb.

A quick demo of one channel only, showing the various step lengths, gate time and pitch control voltage ranges – 2.5v, 5v, 10v. As there is no quantizer, it is obviously easier to get the right pitches quick using the 2.5v range.

This is a unique build of three 104s bolted together, matching the width of an ARP 2600, which it is usually used with.