MacOS was
the first introduced in 1985 with Apple’s Macintosh computer. At the launch, it
was known as “system”. It was the first operating system to be based on
graphical user interface (GUI) and that it stands apart from the other
operating system. Also one does not need to have a hold on command like in
MS-DOS. But there were certain loopholes in this OS. It did not support
multi-tasking, that mean you could run only one application on it at a one
time. Apart from that there were also compatibility issues with other OSes.
Multitasking was brought in MacOS with the release of the system5. But the
major upgrade in this series was System7.