Personal Computer Systems in Operating System:
Computer hardware in the past has been very expensive. A single machine might have many users to keep costs down. This resulted in operating systems focusing mainly on efficiency and protection. It is now possible for individuals to have separate machines as the hardware has become cheaper. The operating systems for personal computers can adopt technology that was originally developed for larger operating systems.
Personal computer systems are primarily designed for a single user environment. They are not too concerned with protection because only one user accesses the machine.