Windows NT - a complete rewrite of windows, and became the core of XP and windows server. This was a major success, IMO, NT/XP was far, far more stable than the 3.1/95 family.
It also took Microsoft almost 10 years and millions of man hours to get NT to a stable state, iron out comaptibility and performance issues before they eventually replaced 95 with XP. It was a huge undertaking - probably not something a startup can afford. IIRC Microsoft had a completely separate team working on Win NT initially, lead by David Cutler.
edit: fixed 'not something a startup can't afford' -> 'not something a startup can afford'
Hmm, that's interesting. I was about to say that NT wasn't a rewrite but it was a completely different operating system designed from scratch, well I guess a little of the design came from VMS:)
I see your point on how you consider this to be a rewrite.
I guess the question I have is, what's the difference between a brand new product, and a rewrite? Up until now I considered windows NT to be a brand new product.
