Can one drive be used to back up multiple computers each using Time Machine?
We have two laptops and a desktop computer in one house on one WiFi system, will one external drive work for all three computers as a system backup or does each computer need their own hard drive?
You can use the same external drive to backup different macs. I used this to backup difference Mac's at work - to transfer user from 1 computer to another, or simply back it up incase I mess up the computer before making changes. Just need to enable Time-machine on each Mac, and it will do it's job.