Hardware quick-fire questions

How do I roll back to Lion or earlier?

> Apple still sells Lion and Snow Leopard on their website. Both cost £19.99. Snow Leopard comes on installation DVDs but Lion is only sold as a download code. If you need physical media, you can buy USB sticks with the Lion installer on them from Amazon for around £15.

How big does the external install disk need to be?

> The OS X installer will fit into 8GB, so you can use a thumb drive if you want.

I entered the Terminal command but my keyboard stopped working!

> The sudo command needs your password but Terminal won’t display the admin password on the screen, so it looks like the keyboard isn’t working. Just type it in blind and hit return.