Project 0: Jump Start

Fall 2026

Due: Friday, October 2, at 11:59pm

Note: This is an individual assignment. Each student must submit a copy of their session's output.

In this pre-project you will familiarize yourself with the course environment (e.g., making sure you can login and prep for working on the project), and compiling and running Nachos. The tutorial below should not take that much time; if you seem to be having serious problems, check Piazza to see if others have reported the same problem and post a note if not.

Nachos is a Java application written to perform the functions of a real operating system. The details of how the operating system implements concepts such as threading, virtual memory, and processes are exposed to you. All of the source code implementing the Nachos operating system is included with the distribution. However, this baseline implementation does not implement some very useful features. During the quarter, you will complete the missing portions of the operating system and use the functionality in your projects.

Every student will do project 0 individually. When we start project 1, you will be working in groups and we will provide each group with a github repo initialized with a fresh nachos source distribution. As a result, you can discard the nachos source you used for project 0 once we start project 1. It also means that you can experiment with the project 0 source however you like — no changes you make to the source in project 0 will propagate to the later projects.

Tasks

This week decide on a group for projects 1–3 and submit your group info in the signup form by Fri Oct 2 11:59pm.
Whether you are working on a desktop in the lab or your laptop, login to ieng6 using an ssh client. Login using your normal UCSD student account, and be sure to prep for CSE 120 when you login. (Some students, such as concurrent enrollment students, may have a cs120**** course-specific account.) If you run into any issues running any of these commands, or if your enrollment is still pending, see the troubleshooting tips page.
```
$ ssh account@ieng6.ucsd.edu
To begin work for one of your courses [ CSE120_FA26_001 ], type its name
at the command prompt.  (For example, "CSE120_FA26_001", without the quotes).
$ CSE120_FA26_001
[...] - Prepping CSE120_FA26_001
```
Download the Nachos distribution into your home directory on ieng6, and then unpack it:
```
$ wget 'https://cseweb.ucsd.edu/classes/fa26/cse120-001/projects/nachos-cse120-fa26.tar.gz'
$ tar xvfz nachos-cse120-fa26.tar.gz
```
Also take some time to read the instructions for all projects on the main projects page.
The Nachos distribution is organized into different directories. Some directories store the Java source code files (e.g., machine, threads, userprog, etc.). Other directories are build directories and do not have any source code files in them (e.g., proj0, proj1, etc.). As the next step, go into the proj0 build directory and compile Nachos for this project:
```
$ cd nachos/proj0
$ make
```
You can safely ignore any compiler warnings. Then run the nachos program:
```
$ nachos
```
The nachos command is a script that invokes the Java VM to run Nachos. It should already be in your path, and you can also find the script in bin/nachos. Running the program causes the methods of nachos.threads.ThreadedKernel to be called in the order listed in threads/ThreadedKernel.java:
1. The ThreadedKernel constructor is invoked to create the Nachos kernel.
2. This kernel is initialized with initialize().
3. This kernel is tested with selfTest().
4. This kernel is finally "run" with run(). For now, run() does nothing, since our kernel is not yet able to run user programs.
Your session should resemble the following (but does not have to be exactly the same):
```
$ cd nachos/proj0
$ make
$ nachos (equivalent to ../bin/nachos)
nachos 5.0j initializing...
 config
 interrupt
 timer
 user-check
 grader

*** thread 0 looped 0 times
*** thread 1 looped 0 times
*** thread 0 looped 1 times
*** thread 1 looped 1 times
*** thread 0 looped 2 times
*** thread 1 looped 2 times
*** thread 0 looped 3 times
*** thread 1 looped 3 times
*** thread 0 looped 4 times
*** thread 1 looped 4 times
Machine halting!

Ticks: total 2130, kernel 2130, user 0
Disk I/O: reads 0, writes 0
Console I/O: reads 0, writes 0
Paging: page faults 0, TLB misses 0
Swap: COFF reads 0, swap reads 0, swap writes 0, swap skips 0
Network I/O: received 0, sent 0
```
Now go back up into the source directories (e.g., machine, threads, userprog, etc.) and trace the execution path by hand to find where the output is coming from (i.e., which classes are generating those output statements). Your job will be simple for this initial project, just modifying a print statement. Specifically, change the Nachos print statement:
```
*** thread n looped m times
```
to
```
*** awesome thread n looped m times
```
And that's it. There are no tricks or edge cases, you just need to follow the instructions.

Code Submission

For this project, each student must submit their project using a script we provide. Go to your top-level nachos directory (not the nachos/proj0/nachos subdirectory) and run the submit-proj0 script:

$ cd ..  [assuming still in nachos/proj0 dir, cd up to the nachos/ dir]
$ pwd    [make sure we're in the nachos/ dir]
/home/linux/ieng6/<account>/.../nachos
$ ls     [doubly make sure we're in the nachos/ dir]
Makefile  ag   machine  proj0  proj2  security  threads   vm
README    bin  network  proj1  proj3  test      userprog
$ submit-proj0

If you get a "command not found" error when running submit-proj0, make sure you have prepped for CSE 120 and also see the troubleshooting tips page.

The output of submit-proj0 should resemble the following. The output will not be exactly the same (e.g., file sizes will differ), and that's ok!

Creating turnin...
NNN bytes written
Turnin created successfully: /home/linux/ieng6/CSE120_FA26_001/turnin.dest/account.tar.gz

There are no tricks or edge cases to test for, you just need to follow the instructions.

You will have until the posted due date to submit the project. You can submit as many times as you like. The last version submitted before the due date will be the one accepted. The script submits your project but does not grade it. We will grade all submissions after the deadline, and we will notify everyone when we have posted the scores to Canvas (the project 0 score will be empty in Canvas until we grade and post the scores). You do not need to submit anything on Canvas, and you do not need to ask to have your submission confirmed. Running the script is sufficient.

Troubleshooting Account Issues

If you encounter problems with your account (command not found, disk quota exceeded, ssh fails, etc.), see these troubleshooting tips.