The Plan.

These steps are not necessarily sequential or in order.

1. We have already been able to read an executable file from fake
   magnetic tapes and run it (class 7, 2nd February).
   Now load up your basic file system with a few executable and
   data files, and be able to run executables from your own disc
   file system.

2. Make a better, more sophisticated file system, and make sure
   you can do step one with it.

3. We can already have two functions timesharing, running concurrently
   (class 11, 16th February).
   Become able to load two or more programs from your disc file 
   system and run them concurrently.

4. We can already read from the keyboard asynchronously, using 
   interrupts (classes 10 to 11).
   Make inno() and inch() (or your own versions of them) work with
   keyboard interrupts so that your time sharing programs can interact
   with the user. Remember all the buffers and race conditions.

   (control characters to get attention)

5. We can already build page directories and page tables and put 
   "OS" code in high addresses and run things in user mode in lower 
   addresses (class 16, 3rd March).
   Now build the page tables as before, but read a separate executable,
   the real operating system (designed to run only when VM is active)
   from your disc file system, and let it take over.

6. Make that OS able to create new processes (with their own page 
   directories and some of their own page tables) to run programs
   in user mode in low addresses at the command of the user.

7. Keeping the results of steps 3 and 4 in play of course.

8. Access to the file system should be through special system calls
   that can run in system mode.

9. You've got an actual multiprocessing operating system now.

10. Make a good newvec and freevec, and let the OS allocate extra
    pages of memory to a process when appropriate.

11. Make it all nice and interesting.