Like most local service airlines Southern flew only Douglas DC-3s for the first few years. In 1961 they began adding 22 40-passenger secondhand Martin 4-0-4s acquired from Eastern Air Lines, newer aircraft that were pressurised and had a rear ventral stairway. The last DC-3 was retired in 1967.
Community Q&A. An operating system (OS) is software that manages the interaction between hardware resources and the programs or applications you use on a computer. Most PCs have a version of the Windows operating system on them but Macintosh, Linux and UNIX are other popular operating systems.
Linux is the most widely used OS. Linux is an open source operating system (OS) for personal computers, servers and many other hardware platforms that is based on the Unix operating system. Linux was originally created by Linus Torvalds as a free alternative operating system to more expensive Unix systems.