How to put boot into interactive mode

[Mike Wright]

04/16/2014 07:24 PM, Robert Moskowitz wrote:
> Long ago I knew a way to get the boot process to require a keystroke at
> each step.  This was important when you were trying to read the screen
> to figure out what is happening, typically wrong.
>
> But long ago I lost my notes on this, and I believe i need before my
> next reboot.
>
> Can someone point me to howto do this?   My search foo is weak....

Booting has become so fast I could no longer hit the key in time but I 
think it was capital I as in interactive.