Mac mode where you can see code on startup In The Outliers, Bill Joy is quoted as saying 


  "If you put your Mac in that funny mode where you can see the code, I
  see things that I can remember typing 25 years ago."


I'm intrigued - what is this mode? How does one use it?
Single user or Verbose mode.
Verbose mode start up

Restart the Mac
Immediately hold down the command + V keys

You have successfully entered verbose mode when you see white text appear on the screen.
See Apple Support