kaled - 2:11 pm on Oct 15, 2008 (gmt 0)

They invented OS that was able to run older software without recompiles.

That's 99% due to the fact that Intel 286 CPUs could run 8086 and 8088 code and the 386 could run 286/86/88 code. All that Microsoft had to do was implement some mode switching code and a compatibility layer - but here's the amazing part - they couldn't even do that themselves they had to buy-in that technology (they were called dos-extenders).

What's more Microsoft did not invent this strategy, the Acorn Archimedes/ARM could run Acorn BBC-Micro programs back in 1987 - that's three years before Windows 3 could run Dos programs (I presume that's what you are referring to). I doubt Acorn were the first either!
As I mentioned before, the Archimedes/ARM could also emulate a PC i.e. it could run DOS software and it could do so faster than typical PCs of the day too!

Kaled.