The A-190.4 is an updated version of the A-190.1, with the addition of a USB input, and a display to show the parameters. (Note that AD5 is not required for this updated module)
The A-190.4 is a MIDI-CV/SYNC interface which can control any A-100 module having CV or Gate input sockets by MIDI. The A-190.4 has two converters which output control voltages from 0V to +5V. CV1 is 12-bit, and “hard wired” to receive MIDI note messages and convert them into control voltages, usually for control of a VCO and giving a resolution of 1/4096th of a semitone. CV2 can be assigned to a MIDI controller and uses 7-bit resolution (1/128th steps). It’s output can be used for voltage control of any suitable module (e.g VCF, VCA etc.). The A-190.4 also has a clock output controlled by MIDI clock. This can be divided down to provide a variety of clock outputs and enable older equipment to be synced to MIDI. A reset output provides control of the A-160/A-161 clock divider sequencer or can produce MIDI synchronized gates (for instance on an ADSR). MIDI START or CONTINUE messages make the voltage at the reset output go low, and MIDI STOP messages make it go high. In addition, the A-190.4 allows for portamento (glide) and pitch-bend and provides a software LFO. These functions can all be switched on and off or altered by MIDI controllers. All control parameters can be saved in non-volatile memory.