Coders at Work: Reflections on the Craft of Programming

by Peter Seibel

So I went off and implemented this file system, strictly on a PDP-7. At some point I decided that I had to test it. So I wrote some load-generating stuff. But I was having trouble writing programs to drive the file system. You want something interactive. Seibel: And you just wanted to play around with writing a file system? At that point you weren't planning to write an OS? Thompson: No, it was just a file system. Seibel: So you basically wrote an OS so you'd have a better environment to test your file system. Thompson: Yes. Halfway through there that I realized it was a real time-sharing system. I was writing the shell to drive the file system. And then I was writing a couple other programs that drove the file system. And right about there I said, “All I need is an editor and I've got an operating system.”