# File lib/FileSystemImage.rb, line 141
def catalog
  s="\n%-32s %-16s %04s   %s\n\n" % ["FILENAME","TYPE","LENGTH","LOAD ADDRESS"]
  self.files.sort.each do |file|      
    raise "bogus file '#{file.filename}'" if file.contents.nil?
    contents_length= (file.contents.respond_to?(:length) ? file.contents.length : 0)
    s<<"%-32s %-16s $%04x    $%04x\n" % [file.filename,file.type_description,contents_length,file.load_address]
  end
  s
end