The Publison Infernal Machine 90 was the first box that allowed changing the speed without affecting pitch and vice versa. "It is an amazing digital processing unit that has sampling, time stretching, reverberating, phasing, and delay effects. The unit offered an impressive 30 seconds of stereo sampling, rich and endless reverb options and has a distinctive character all its own." It worked really well on vocals. The converters had a mid-fi sound and limited bandwidth but it created a huge buzz at AES when it first came out and was “the predecessor for Autotune”. Many major studios had an Infernal Machine back in the 80's and early 90's.
"Chemical Brother Tom Rowland notes "it was a favorite machine of Ivan 'Doc' Rodriguez who worked on Boogie Down Productions, Grandmaster Flash, Spoonie G, T-LaRock, Biz Markie, Big Daddy Kane, Run DMC, LL Cool J and others" [including Eric B & Rakim's Paid In Full and records by EPMD]. But they were widely used in other genres besides hip hop (Prince was apparently a fan of the Publison) despite it's reputation of being very unreliable and difficult to repair,
DBM Pro Audio/Music Services was one of the few places that could service a Publison. Not sure if they still do.