Let's see: IBM's APL and Call/360 both provided an integrated program editing and execution environment (supporting Basic, Fortran, and maybe PL/I in the latter

Let's see: IBM's APL and Call/360 both provided an integrated program editing and execution environment (supporting Basic, Fortran, and maybe PL/I in the latter). By 1970, Basic had spread to all sorts of systems (I got paid for writing software for Computer Sciences Corp's Basic system at that time). I used a similar PL/I-based system at that time, from a company whose name I have forgotten. And in the 1970s, I was busily using the Michigan Terminal System, which provided a nice complement of languages, including LISP/MTS and ALGOL W, along with a powerful text editor and debugger. It also provided reasonably rapid feedback, if you had enough computer dollars [sic]. I might also mention the MCM 70, a Canadian microcomputer that provided most of APL\360 in a $5000 package; that dates from 1974, and anticipates IBM's later 5100. Interlisp has already been mentioned, though the Lisp REPL goes back to the early 1960s. The good folks at Xerox PARC were under way with their Smalltalk work by the mid-1970s. Reading the article, I was not clear on the author's definition of “IDE”, or why the Maestro I was the first.