We've posted the PDF of David Allen's software drawings from 1994. This is what David had to say about the drawings:
At the GTD Summit I briefly shared a vision of the “ultimate GTD app” which consists of 19 pages of hand-drawn drafts of the screens I would want to use. I just said to myself, “Can I click F1 on my computer and get to a clear head?” I spent two days creating those screens.
Since I drew these, we’ve invested in two serious attempts at producing a software product that would do it (or at least come close). Both ended in a “not yet” conclusion, after tremendous research in the tech and analysis of the market (one in the mid-1990s and the last in the mid-2010s.) Our partners in these enterprises were the best and brightest you could possibly gather to explore this. But the technology required to make some simple GTD practices happen, and the lack of awareness in the marketplace for such a tool, put a kibosh on both endeavors.
So I promised our hundreds of people at the GTD Summit that I would make those screens available to the public. This was originally legally protected IP; but I decided to just make it “open source” now in case any of you out there could make it happen.