When Gates made that infamous remark, the most widely used business PC operating system was CP/M. Most versions of CP/M only supported 64 KB of RAM. By contrast, PC-DOS (MS-DOS) supported 10 times as much. Given that people were doing productive work on the 64 KB CP/M systems, it was hard to imagine at the time that 10 times as much RAM wouldn't be enough for anyone. Also keep in mind that even many mainframe computers of the day didn't have much more RAM than that and they supported multiple users. How could anyone ever use up 640 KB of RAM for a single user system?

Well, for starters, when the RAM expanded, so did the code. Most commercial products on the CP/M systems were written in highly optimized assembly language. With "so much" RAM to play with, many developers switched to less optimized languages like C which produced larger programs. So what if C code ran slower than assembly code? We had those screaming 4.77 MHz 8088 processors! Why waste time and money optimizing programs when you had that much power on your desktop?

Of course, had Bill been invited to visit the Xerox Palo Alto Research Center (PARC) like Steve Jobs, he would've seen the future in operation. PARC invented it all - desktop systems linked by Ethernet running GUIs, laser printers, email, etc. Too bad the corporate officers lacked the vision of the PARC pioneers. They could've owned it all.