Microsoft C compiler v4.0 and CodeView in the mid 80s
That was indeed a solid product. IIRC, it was basically a repackaged version of a compiler/debugger by a company they bought. (Whitesmiths?)
It took a while, but they eventually f*&^#d it up: it turned into VisualStudio.
Nope, I misremembered. The first couple versions of Microsoft C were repackaged versions of Liveboat's Lattice-C compiler. Supposedly versions 3 and up were developed entirely by MS: