file-related commands:
   `pwd` -- print working directory
   `cd "path"` -- change directory
   `dir` -- list files
   `mkdir "dirname"` -- make directory
   `load "filename"` -- load program
   `save "filename"` -- save program
   `view "filename"` -- preview file	
		
Note that there are two disks available:
    `"/sys"` -- system disk (read-only)
    `"/usr"` -- user files (read/write)

To find the fun stuff, enter: 
  `cd "/sys/demo"`
  `dir`
