"You could play one keyboard with your right hand and another keyboard with your left hand," says Dave Smith, a synthesiser manufacturer from California who was working on the issue back then.
"But [musicians] couldn't play more than one at the same time because there was no way of electrically interconnecting them," he remembers.
What Smith did next would transform the way recording studios worked, and create a revolution in music and recording production.
He persuaded manufacturers to adopt a common format which allowed their synthesisers to be controlled externally - by another keyboard potentially made by a rival manufacturer, or even by a computer.
It was called Musical Instrument Digital Interface (MIDI) and would soon become the industry standard for connecting different makes of synthesisers, drum machines, samplers and computers.
http://m.bbc.co.uk/news/technology-20425376