My first operating system project was to build a real-time system called RSX-11M that ran on Digital's PDP-11 16-bit series of minicomputers. ... a multitasking operating system that would run in 32 KB of memory with a hierarchical file system, application swapping, real-time scheduling, and a set of development utilities. The operating system and utilities were to run on the entire line of PDP-11 platforms, from the very small systems up through the PDP-11/70 which had memory-mapping hardware and supported up to 4 MB of memory.

Unix is a junk OS designed by a committee of PhDs.

In the summer of 1988, I received an interesting call from Bill Gates at Microsoft. He asked whether I'd like to come over and talk about building a new operating system at Microsoft for personal computers. What Bill had to offer was the opportunity to build another operating system, one that was portable.

My first operating system project was to build a real-time system called RSX-11M that ran on Digital's PDP-11 16-bit series of minicomputers. ... a multitasking operating system that would run in 32 KB of memory with a hierarchical file system, application swapping, real-time scheduling, and a set of development utilities. The operating system and utilities were to run on the entire line of PDP-11 platforms, from the very small systems up through the PDP-11/70 which had memory-mapping hardware and supported up to 4 MB of memory.