@jalefkowit
>Those older chips always ran in "real mode," where memory locations had fixed addresses, and any running program could modify the contents of any address. This meant that you couldn't have two programs running at once, because one might try to use a bit of memory the other was already using, and blammo!

This isn't the reason why it couldn't. For one, Windows CE and older versions of MacOS (<10) didn't have memory protection either.