I think I bought my 8K Microsoft Basic rom for th Rockwell Aim 65 in 1978. To me (in Europe) Microsoft already was an institute, an authority. But Basic was Texas Instruments calculators and school (arrays and mathematics), Forth was HP reversed polish notation, electronics and fun. I studied for weeks, but - just as with the 8K Monitor rom of the Aim 65 - I couldn't make the connection between the assembly opcode and what was going on functionally. It just went over my head. The 4 K Forth rom was easy: if you understood defining words (especially the Next-interpreter) you understood it all. Besides, most of Forth was written in Forth.
I think what killed Forth was that it was Open Source (the term then, slipped my mind). I wonder what would have happened if Bill had gone for Forth in those days. I think, we would have had totally different boundaries regarding opcode, operating systems, languages, applications etc, than we do today. A lot of what the CLR, managed code, .Net Framework and the like is meaning to us, would have been intrinsic in my view. Anyway, Microsoft today is an ashtonishing feat, with a lot more to come probably.