Retro Thing has published an interesting article that takes a look at an early Hungarian computer music interface, the Muzix 81 system:

In 1981, Hungarian musician and physicist Andras Szalay visited Sinclair in Cambridge where he bought a Sinclair ZX81 kit and built a computer at home. He designed an interface called the Composer, the first part of the powerful Muzix81 system, in 1982.

The Composer was a pre-MIDI sequencer software with a dedicated hardware interface for synthesizers and drum-machines. It used control-voltage. The interface featured two CV outputs and two inputs for both the Roland and Yamaha implementations (in other words, any synthesizer could be connected to the interface, be it Moog, Arp, Korg, Roland, etc.) The Composer software enabled the user to record, edit and play sequences. The sequences could be arranged into a song. A cassette recorder attached to the interface stored the songs or sequences. The Composer software could also randomly delay certain notes to add swing/shuffle/humanize to the sequence.

Szalay and his brother went on to add some very interesting features to the Muzix system, including sampling and MIDI. About 300 of the systems were eventually sold.