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Interdesign was a company founded by Hans Camenzind the inventor of the NE555. I've always thought the cover of this brochure was a work of art. I've been unable to find a copy on the web and not much information on Interdesign is available so I decided to scan a copy for historical purposes.
They designed a chip set for us when I was working at "Variable Speech Control Company" back in the early 1970s. Hans and his engineer Jim Ball designed a 4 Monochip solution for our Speech pitch shifter. Blind people could use VSC to playback talking books at 2x or higher speed with decent intelligibility thanks to corrected pitch. There was also interest in slowed down recordings with the pitch shifted up (for learning foreign languages or understanding garbled messages).
The 4 semi-custom Monochips working together provided ramped clocks to generate the pitch shift through Bucket Brigade Analog Shift Registers. Then they managed zero cross detection so they could blank out the discard audio with minimal perturbations.
[edit] The Monochip technology is an interesting approach to make semi-custom ICs. A basic substrate containing multiple active devices and passive components (including pinch resistors) and fabricated except for the final top metallization layer that like circuit board traces connect the sundry devices together into functional circuitry. I recall seeing a Rubylith(?) the optical pattern for the metallization layer. Like a PCB design this was done blown up to many times real size. /edit]
Smart guys...
JR
Cancel the "cancel culture", do not support mob hatred.
