From Joel's classic article: "Microsoft almost made the same mistake, trying to rewrite Word for Windows from scratch in a doomed project called Pyramid which

From Joel's classic article: "Microsoft almost made the same mistake, trying to rewrite Word for Windows from scratch in a doomed project called Pyramid which was shut down, thrown away, and swept under the rug. Lucky for Microsoft, they had never stopped working on the old code base, so they had something to ship, making it merely a financial disaster, not a strategic one."