Sources? No. But the first IDEs were products like Turbo Pascal, and the term originated to distinguish them from the official Microsoft C Compiler environment (and others: Mark William's C, etc...) which was unix-like.
Sure they are, but they were't marketed using the term "IDE". That acronym appeared AFAIK in the late 1980's in the IBM PC world, and it was used to distinguish those software products from the unix-like MS tools.
> The Symbolics 3600 is a 36-bit single-user computer designed for high-productivity software development and for the execution of large symbolic programs. ...
> The system software constitutes a large-scale programming environment ... Object-oriented programming techniques are used throughout the 3600 system to provide a reliable and extensible integrated environment without the usual division between an operating system and programming languages ...
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There you have 'development' and ' extensible integrated environment'.
