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.
Desktop PC. Multitasking operating systems can run more than one program at the same time. A computer's operating system is one of its most important aspects. An operating system can be used to managed files on a computer hard drive. A central processing unit.