I'm so old, I watched Richard write Scandisk! I was an intern at Microsoft in '93 in MS-DOS, and while I was working away on Smartdrv and so on, @lertulo was an intern writing scandisk in the office next door... And yes, it surprised me too that as interns we were working on actual, important shipping features, but I think most of the senior devs were embroiled in rewriting DoubleSpace to avoid the Stacker patent at the time... In any event, as I recall it, Richard wrote the whole Scandisk app in pure x86 assembly, including his own screen UI, widgets, progress bars, and all of that. Oddly, there were no shared code libraries in MS-DOS. So if you needed to convert HEX to Decimal ASCII, you did it yourself for the millionth time in assembly. Why he chose not to use the UI framework from the Edit command I'm not sure, but I assume he had his reasons. What I remember most is that he coded it all in vi, and he was a master with it. I've been using vi casually for 40 years, and I know about eight commands. But his hands were just a blur of weird search tags and hotkeys... I learned a ton just sitting on a chair in his office, asking too many questions, and generally being annoying - picking his brain! He never ultimately did go on to work for Microsoft, much to our loss, I'd say.