Christopher, W. A., Procter, S. J. & Anderson, T. E. (1993), The nachos instructional operating system, in `USENIX Winter', pp. 481--488.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....a machine dependent part handled by the Exception class together with its concrete processor and machine dependent subclasses, and a machine independent part which the higher levels refer to via machine independent exception types. The port of the nano kerncl to Solaris is similar to Nachos[12]. Nachos is a multithreaded operating system simulated as a regular Unix process. It was developed for pedagogical purposes. VirtualChoices is different in that we use real OS code that is not stripped or simplified. VirtualChoices also provides multiprocessor support, with physical processors ....

W. A. Christopher and S. J. Procter and T. E. Anderson. The Nachos Instructional Operating System. Technical Report UCB//CSD-93-739, University o California, Berkeley, April 1993. 11

....well across a spectrum of top ics. One standout has been the MiPS architecture, which has served as a useful tool in the domains of both operating systems and machine architecture pedagogy. This is demonstrated by the number of educational projects based on MIPS, such as SPIM [3] MPS [2] Nachos [1], and descendants of MiPS such as DLX [4] Once again, however, the sheer number and diversity of tools based on this architecture seems to imply that the situation could be improved. With Ant 32, we plan to combine the ed ucational features of most of these tools into a sin gle, coherent ....

W. A. Christopher, S. J. Procter, and T. E. Anderson. The nachos instructional operating system. Proceedings of the USENIX Winter 1993.

....the project, as well typical figures for the amount of code the students write. 4 Related work PortOS has been used as the project for our honors level operating systems course. In this respect it is comparable to other instructional operating systems which have been described in the literature [3, 12]. We briefly elaborate the differences between PortOS and these systems, as well as other styles of operating system projects. q ne Figure 3 . A topology file and the corresponding broadcast network. quark .xx.x proton x.xx. neutron xx. electron .x. x neutrino x. x. neutron neutrino ....

....958 1500 Testing code for all phases 1890 Table 1. Line counts for PortOS components. Students start with the PortOS Core, and are successively provided extra code in each of the phases. The final column lists the typical length of an adequate solution. Our work is closest to Nachos [3] in form and content, but focuses more on advanced projects. PortOS enables real code to be linked to the kernel, rather than relying on crosscompilation and simulation, which require a special build, test and debug environment. Finally, it supports the Windows operating system family, including ....

W. Christopher, S. Procter, and T. Anderson. The Nachos instructional operating system. In Proceedings of the 1993.

....impossible. 08 17 19 03 11 23 05 17 19 03 05 23 peephole for sequence of used modules communication process other processes service access point (SAP) CP M MS DOS SAP exchange drivers exchange modules display MBR hardware SAP Figure 1: Our old exercise system 1. 2 Nachos [4], Minix [5] Both systems belong to the category of experimental operating system. The student gets the source code of the operating system. His problems are to design and to implement parts of the operating system. The principal fault of these systems is the complexity. The student has to look at ....

Christopher, W.A., Procter, S.J., and Anderson, T.E.: The Nachos Instructional Operating system. Berkeley: University of California Berkeley, 1993.

....hands on experience with operating system internals. By using a proprietary Unix operating system, the students did not get an opportunity to even study, let al..one implement, real operating systems code. We had considered switching to an operating systems simulation environment such as Nachos [CPA93] or others [KS91,GBC 99] but had not moved in that direction because while students implement operating system code, they do so in a simulated operating system. We did not believe this was an improvement over the current approach. Systems curricula must address the fact that operating systems ....

W. Christopher, S. Procter, and T. Anderson. The Nachos Instructional Operating System. Technical Report CSD-93-739, University of California at Berkeley, 1993. URL: http://www.cs.berkeley.edu/~tea/nachos/index.html

....a machine dependent part handled by the Exception class together with its concrete processor and machine dependent subclasses, and a machine independent part which the higher levels refer to via machine independent exception types. The port of the nano kernel to Solaris is similar to Nachos[12]. Nachos is a multithreaded operating system simulated as a regular Unix process. It was developed for pedagogical purposes. VirtualChoices is different in that we use real OS code that is not stripped or simplified. VirtualChoices also provides multiprocessor support, with physical processors ....

W. A. Christopher and S. J. Procter and T. E. Anderson. The Nachos Instructional Operating System. Technical Report UCB//CSD-93-739, University of California, Berkeley, April 1993. 11

....as the design and implementation of real operating systems. I will argue that the former is very di#cult to teach well, and that it can be taught better with the help of a system that can be used to model and prove properties about concurrent programs. 2 What s Wrong with Nachos and Minix Nachos [1], Minix [5] and XINU [2] are operating systems designed to teach operating systems. The premise is that a simplified system will contain the essential structure, without bogging students down with the irrelevant details that pervade a real OS. This logic is sound with respect to teaching ....

....that pervade a real OS. This logic is sound with respect to teaching operating systems design and implementation; however, it does not carry over to teaching concurrent programming, which the student is usually expected to pick up along the with rest. For example, we find the following quote in [1]: When we first used Nachos, we omitted many of the practice problems we now include, thinking that students would see enough concurrency in the rest of the project. In retrospect, the result was that many students were still making concurrency errors even in the final phase of the project. ....

Wayne A. Christopher, Steven J. Procter, and Thomas E. Anderson. The Nachos Instructional Operating System. Computer Science Division, University of California at Berkeley.

....functions, or code frameworks, in different semesters. Large and captivating assignments require significant resources to prepare. Our project attempts to address this issue in the context of CS 2. Similar projects address these issues in a Compilers Course [2] and an Operating Systems course [5]. Each module supplies a situated learning experience [12] that engages students from the outset by providing practical and illuminating examples for how and why data structures are used. Applications are graphical where appropriate, integrate several data structures into real world programs, and ....

CHRISTOPHER,W.,PROCTER,S.,AND ANDERSON, T. The Nachos instructional operating system. 1993 Winter USENIX Conference (January 1993), 479--488.

....instances of the same course, but projects are not routinely shared between institutions or even between instructors at the same institution. In contrast, other areas of computer science do have widely used course projects (e.g. Tom Anderson s nachos project for teaching operating systems [CPA93]) This work was supported by an NSF NYI award. 1 The current situation would improve if instructors who design course projects shared the fruits of their labor more widely. This article presents Cool, a freely available, portable compiler project. Cool has been used for the past two years in ....

W. Christopher, S. Procter, and T. Anderson. The Nachos instructional operating system. In 1993 Winter USENIX Conference, pages 479--488, January 1993. 5

....on NEWmacboot. This takes much less time. 5 Alternative Approaches for OS Labs There are other approaches to providing practical learning experiences for students: computer and operating system simulators [3, 6] and small operating system kernels running on the hardware [4, 5] Nachos y [1] is a very simple, but functional, operating system for emulated hardware consisting of a network of MIPS like workstations. In a series of projects, students design and implement improvements to the functionality and performance of the major components of Nachos. The C language is used and the ....

W. A. Christopher, S. J. Procter, and T.E. Anderson, "The Nachos Instructional Operating System," Proc. 1993 Winter USENIX Conference, January 1993, pp. 479-488. y Available by anonymous ftp from ftp.cs.berkeley.edu in directory ucb/nachos.

....worthwhile investigating these parameters, particularly when process cache footprints are considered. A better approach would be to use an operating system simulator that could thoroughly model the sequence of events in a context switch. Several such simulators are available, for example Nachos [Christopher et al. 1998] and SimOS [Rosenblum et al. 1995] Given enough resources, it may even be possible to implement an experimental context switching RAMpage system on a real operating system for which the source code is freely available, such as Linux. 57 ....

W Christopher, S Procter and T Anderson. The Nachos Instructional Operating System, Technical Report, University of California at Berkely. http://cs-tr.cs.berkeley.edu/TR/UCB:CSD-93-739

....the design and implementation of real operating systems. I will argue that the former is very difficult to teach well, and that it can be taught better with the help of a system that can be used to model and prove properties about concurrent programs. 2 What s Wrong with Nachos and Minix Nachos [1], Minix [5] and XINU [2] are operating systems designed to teach operating systems. The premise is that a simplified system will contain the essential structure, without bogging students down with the irrelevant details that pervade a real OS. This logic is sound with respect to teaching ....

....that pervade a real OS. This logic is sound with respect to teaching operating systems design and implementation; however, it does not carry over to teaching concurrent programming, which the student is usually expected to pick up along the with rest. For example, we find the following quote in [1]: When we first used Nachos, we omitted many of the practice problems we now include, thinking that students would see enough concurrency in the rest of the project. In retrospect, the result was that many students were still making concurrency errors even in the final phase of the project. 3 ....

Wayne A. Christopher, Steven J. Procter, and Thomas E. Anderson. The Nachos Instructional Operating System. Computer Science Division, University of California at Berkeley.

....by registering handlers, catching signals associated with IO, virtual memory, timers, instruction faults, etc. and by manipulating the signal mask to mask and unmask interrupts. Table 3 shows the correspondence between hardware interrupts and Unix signals used. VChoices is similar to the Nachos[8] instructional OS in that it runs as a Unix process. VChoices is different in that it not stripped down and simplified, nor do we interpret application code. VChoices also provides multiprocessor support, with physical processors simulated as separate Unix processes. This allows simulated CPUs ....

W. A. Christopher and S. J. Procter and T. E. Anderson. The Nachos Instructional Operating System. Technical Report UCB//CSD-93-739, University of California, Berkeley, April 1993.

....protocols. Furthermore, process emulation in the form of direct execution is restricted to the execution of a single instance of the protocol running on the operating system. We are proposing the execution of protocols on a simulated network environment, rather than in a single OS context. Nachos [15] and SimOS [64] are other process emulation environments that operate at the granularity of individual instructions. Nachos is a centralized process emulation environment that simulates the MIPS R2 3000 integer instruction set. SimOS is a distributed process emulation environment that supports the ....

W.A. Christopher, S.J. Procter, and T.E. Anderson. The nachos instructional operating system. Nachos is available at ftp://sprite.berkeley.edu/nachos/.

....was developed independently during the period in which SunOS Minix was written. A detailed comparison with SunOS Minix is not possible at this point because all documentation on VXinu is written in Japanese. ffl Nachos is a very small instructional operating system that runs as a Unix process [4]. Its functionality is limited in many areas because of a desire to keep the amount of code to a minimum and because a set of projects used with Nachos requires students to implement (or reimplement) substantial components of Nachos. Nachos does, however, include some features (basic network ....

Wayne A. Christopher, Steven J. Proctor, and Thomas E. Anderson. The Nachos instructional operating system. In Proceedings of the 1993 Winter USENIX Conference, pages 479--488, January 1993.

....an operating system typically requires two machines: one as the target while the other runs a debugger such as GNU s gdb. The expense of such setups contributes to the difficulty of developing operating systems directly on bare hardware. A number of instructional operating systems, such as Nachos[13], its predecessor TOY, and the operating system simulator used at the University of Illinois[7] run as regular UNIX[9] processes. The operating system is simulated within the UNIX process. This removes the impediment of requiring target machines in order to run the system. Students run and debug ....

W. A. Christopher and S. J. Procter and T. E. Anderson. The Nachos Instructional Operating System. Technical Report UCB//CSD-93-739, University of California, Berkeley, April 1993.

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Christopher, W. A., Procter, S. J. & Anderson, T. E. (1993), The nachos instructional operating system, in `USENIX Winter', pp. 481--488.

No context found.

W. A. Christopher, S. J. Procter, and T. E. Anderson. The nachos instructional operating system. In Proceedings of the Winter 1993.

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Wayne A. Christopher, Steven J. Procter, and Thomas E. Anderson, "The Nachos Instructional Operating System", in Proceedings of the Winter 1993 USENIX Conference, pp. 481-489, Jan 1993.

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