When I was an intern on MS-DOS in '93, one of my last projects was the "StepUp!" upgrade: putting the entire MS-DOS upgrade on a single floppy disk. Normally, it was 3-4 disks, so saving a couple of bucks on each copy, times a few million copies, would save the company bajillions of dollars. My cut of that? Perhaps a full-time offer if I did it well. And so, thanks in part to some help from the big brains we had recently acquired from FoxPro, I modified MS-DOS Setup to apply binary deltas instead of shipping entire files. It was, of course, all done in pure x86 assembly language, as was the style at the time. It's not a hard problem until you have to write it; and you're just learning x86, and there's no Internet yet! The "rate of churn" in most MS-DOS binaries from one version to the next was usually very low. As a result, the actual delta from the previous version was small, and it all fit on a single floppy. Bajillions saved! And a job offered :-)

Hey look, it's your old friend Task Manager... on the Mac!