Secuenciador analógico de dos filas de 8 pasos y dos filas de potenciometros de control 

Features of the analog rows (knobs): 
- 8 potentiometers (knobs) 
- lower row: Scale (knob), upper row: 1V/2V/4V 
(octave range switch for exact VCO control) 
- Glide time (knob), same as portamento or slew limiter 
- Glide Control (control input for switching glide on/off) 
- S/H Control (control input for internal S and H, works like A-148) 
- Pre Glide/S and H-Out (analog output before S/H and glide unit, especially required when external audio signals are used as inputs of the lower row) 
- Post Glide/S and H-Out (analog output after S/H and glide unit) 
- lower row: external inputs for the 8 steps (switched jack sockets), control signals or audio signals may be used as inputs (allowed voltage range -5V...+12V), the knobs of the lower row are working in this case as attenuators 

Features of the trigger rows (switches): 
- 4 Trigger/Gate tracks with 2 rows of switches 
- toggle switches of 1-0-1 type (with middle position), which can be used to send a trigger/gate to the track above or below or to send no trigger/gate (middle position) 
- 3 trigger rows (i.e. short pulse for each step set, pulse width corresponds to the pulse width of the clock/step input signal) 
- 1 gate row (i.e. a high signal is applied during the length of the step set)

Control inputs and buttons: 
- Step (defines the tempo of the sequence, same as clock or trigger input)
- Reset (resets all rows to step 1) 
- Start (starts the sequence at the momentary position) 
- Stop (stops the sequence at the momentary position) 

Step and Reset are compatible to the MIDI interface A-190, i.e. in combination with the A-190 the A-155 may be synchronized via MIDI. 
The quantizing module A-156 can be used to quantize the infinite analog voltages coming from A-155 into discrete semitone steps (multiples of 1/12V). 
Without MIDI interface e.g. a LFO rectangle output can be used to define the tempo of the sequence. 
The sequencer controller A-154 adds a lot of new functions to the A-155 (e.g. voltage controlled addressing, forward/backward/pendulum/random mode, voltage control of first and last step, voltage controlled clock and gate length, step skipping, combination of several A-155 in parallel/serial mode and many more).