Background Windows Subsystem for Linux was developed by Microsoft to enable command line programs compiled for the Linux operating system to be executed on Windows. To explain the architecture I would like to show the evolution of OS design and how that has enabled this subsystem to be built. Dark Ages (or Back in the Day) Microsoft's MS-DOS was quite primitive in its design (compared to today's OS's). It is a single user OS that can execute one process at a time. DOS had an application programming interface to allow user programs to access some hardware in a device independent way, but only for character-based applications. This allowed applications to display graphical elements emulated with text characters as these screenshots of Microsoft word for DOS show: This is Microsoft Word version 1. To use these programs you had to remember key combinations to bring up the menus and used the cursor keys to navigate around the screen. If the a...