This is one of my favorite stories in the annals of computer history. IBM really wanted to use CP/M as the operating system of their new PC. However, the president of Digital Research (which owned CP/M), Gary Kildall, didn't trust IBM (and with good reason). When IBM came around to sign the papers, Gary gave IBM an implicit F.U. by going hot air ballooning that day. IBM turned around and went with choice number two: some guy named Bill Gates. Believe it or not, this is a GOOD thing. Bill Gates was brilliant (in terms of business) and knew IBM was really stupid. While signing, Bill said, "Hey, do you guys mind if I license PC-DOS under the name "MS-DOS" to other personal computer makers? IBM, thinking that the physical hardware was the important part, said, "Sure, go ahead, kid, whatever." Somehow, I doubt if this would have occurred to Gary Kildall. Without that, there would be no IBM compatibles. There would be only one maker of IBM PCs: IBM. IBM is many things; innovative is not one of them. We'd probably still be using line command prompts and floppy discs if it weren't for that.
The Kaypro 2X had floppy discs and the OS froze up if you asked for a disk read while there was no disc in the disc drive. With only 64K of RAM, the OS had to be so compact that there was not enough space for a routine to handle the exception. But that was just operator error. An effor I made from time to time, but not the fault of the OS.