Second this recommendation. Fun read! I know a lot of HN folks won’t be as impressed as I was, but I had no idea they wrote the first several versions of WordPerfect for DOS in assembly. To me, at least, THAT is impressive. I wouldn’t even know where to begin to start a project like that in assembly.
I'd say most software on personal computers prior to the late 1980s was written in assembly. Compilers at the time were terrible at optimization and you could really tell the difference as a user between a compiled program and one written in hand-crafted assembly.