The EMS Synthi (first available in May 1971) was a portable modular analog synthesizer made by Electronic Music Studios of England. The EMS Synthi AKS (March 1972) was a version with a built-in keyboard and sequencer. The synthesizers were used by artists such as Brian Eno and Pink Floyd.
This handbook, presumably produced with an IBM Selectric typewriter, was written by Peter Grogono, a computer programmer who developed EMS software. The diagrams are captioned with IBM’s Script and Light Italic.
Incidentally, about 40 years later, Light Italic inspired Vulf Mono, a font used by audio software company Goodhertz.