Short answers, pulled from the story.
The earliest known tape music composition is The Expression of Zaar by Egyptian composer Halim El-Dabh. El-Dabh recorded sounds of an ancient zaar ceremony in Cairo in 1944 using a wire recorder, then processed the material at the Middle East Radio studios using reverberation, echo, voltage controls, and re-recording. The resulting work was presented at an art gallery event in Cairo that same year.
Musique concrète was a compositional practice based on editing together recorded fragments of natural and industrial sounds. Pierre Schaeffer at Radiodiffusion Française is credited with originating its theory and practice. On the 5th of October 1948, RDF broadcast Schaeffer's Etude aux chemins de fer, marking the beginning of musique concrète as a recognized form.
The Studio for Electronic Music at NWDR in Cologne was officially opened in 1953, though it had been in the planning stages as early as 1950 and early compositions were made and broadcast in 1951. It was conceived by Werner Meyer-Eppler, Robert Beyer, and Herbert Eimert, who became its first director. Karlheinz Stockhausen joined soon after and composed his Studie I there in 1953.
Vladimir Ussachevsky and Otto Luening gave the first tape music concert in the United States on the 28th of October 1952. The concert included Luening's Fantasy in Space and Low Speed, both created at the home of Henry Cowell in Woodstock, New York. Shortly afterward, the two were invited to demonstrate on NBC's Today Show, making it the first televised electroacoustic performance.
The Roland TR-808 was one of the first fully programmable drum machines, released by Roland Corporation in 1980. Yellow Magic Orchestra were the first band to use it in 1980. It gained widespread popularity through Marvin Gaye's Sexual Healing and Afrika Bambaataa's Planet Rock in 1982, and became the drum machine of choice for Detroit techno producers Derrick May and Juan Atkins in the late 1980s.
The Yamaha DX7, introduced in 1983, was the first stand-alone digital synthesizer using FM synthesis and became one of the best-selling synthesizers of all time. It was known for bright tonalities produced in part by its 57 kHz sampling rate. Yamaha had originally licensed the FM synthesis algorithms from John Chowning of Stanford University in 1975, and spent years adapting them before the DX7 reached the market.