Sweet DOS memories. I could probably still remember how to write CONFIG.SYS and AUTOEXEC.BAT files that wring out every possible byte of <640K memory so that Ultima VII would run. (This game had a home-grown memory manager which required an obscene ~620K of so-called "real" memory while also requiring certain drivers that ate into that real memory, making it difficult to run the game without manually customizing the DOS startup command files.)