Peter Norton wrote this in 1983: "The Microsoft C compiler has interesting historical roots. Although Microsoft itself works with C, this compiler is not a dir

Peter Norton wrote this in 1983: "The Microsoft C compiler has interesting historical roots. Although Microsoft itself works with C, this compiler is not a direct Microsoft product. Instead, it is an adaptation of the famous and highly regarded Lattice C compiler." There are also ads like https://archive.org/details/PC-Mag-1984-09-04/page/n51/mode/2up?q=lattice https://archive.org/details/PC-Mag-1984-09-04/page/n51/mode/... saying "Microsoft C compiler / Includes Lattice C and the MS Librarian". I can't find info about v2 or v3. Edit: https://winworldpc.com/product/microsoft-c-c/2x https://winworldpc.com/product/microsoft-c-c/2x says "Microsoft C 1.0 and 2.0 are a rebranded version of Lifeboat Associates Lattice C", so your doubt seems well founded.