Appendix B THE NACHOS SYSTEM

A good way to gain a deeper understanding of modern operating-system concepts is to get your hands dirty — to take apart the code for an operating system to see how it works at a low level, to build significant pieces of the operating system yourself, and to observe the effects of your work. An operating-system course project provides this opportunity to see how you can use basic concepts to solve real-world problems. Course projects can also be valuable in many other areas of computer science, from compilers and databases to graphics and robotics. But a project is particularly important for operating systems, where many of the concepts are best learned by example and experimentation. That is why we created Nachos, an instructional operating system intended for use as the course project for an undergraduate or first-year graduate course in operating systems. Nachos includes code for a simple but complete working operating system, a machine simulator that allows it to be used in a normal UNIX workstation environment, and a set of sample assignments. Nachos