7.6 Operating Systems

Operating systems are the most fundamental of programs, allowing the computer to run programs and communicate with its peripheral devices. Most users have heard of Windows, Unix and the Mac systems, but the full list, with their various versions, runs to several hundred. A few comparisons:

System	Release date	Minimum processor speed	Minimum RAM required	Minimum hard disk space required
Windows XP	2005	300 MHz	128 MB	1.5 GB
Windows Vista	2006	1 GHz	1 GB	15 GB
Windows 7	2009	1 GHz	1-2 GB	16-20 GB
Mac OS 10.6	2009	as supplied	1 GB	5 GB
DOS	1979-1991	90 MHz	256 K	360 K
Unix	1969	200 MHz	32 MB	1.44 MB
Linux	1991	200 MHz	64 MB	1.44 MB
Red Hat	1993	200 MHz	64 MB	1.44 MB

Operating systems have grown more sophisticated, requiring in turn computers with higher processor speeds, more RAM and hard disk space.

Most operating systems have these capabilities:

1. GUI (Graphical User Interface): navigation with a display and mouse.
2. Multi-user: several users can operate the computer at the same time.
3. Multiprocessing: several computer processors can run on the operating system at the same time.
4. Multitasking: several software programs can run on the operating system at the same time.
5. Multithreading : several parts of the same software program can run on the operating system at the same time.

Windows

The Windows operating system was developed by Microsoft, and went through various incarnations: Windows 3x, 95, 98, CE, ME, NT, XP, Vista, and 7. As the name suggests, this most popular of systems operates through a fairly intuitive series of frames and visual devices. Because small differences in versions intended for different areas of the world can cause problems in third-party applications, it is wise to check trial software on all operating systems likely to be used.

Mac OS

Still the favorite of graphic designers, the Mac system provides a screen display similar to that of Windows but one easier to operate in its earlier incarnations than were Windows programs, linking peripherals as 'plug and play', i.e. not requiring small programs called 'drivers' to be first installed.

DOS

The Disk Operating System was the underlying platform for earlier Windows operating systems. Like the Unix systems, its operation was through commands typed onto the screen: a powerful system but not intuitive nor forgiving. Commands had to be learned and couldn't be undone. (Unix commands are even less intuitive, incidentally: for the DOS command 'edit', the Unix command is 'vi'.)

Unix

Unix was developed by members of the Multics team at the Bell labs from the late 1960s, supplemented by work from many other organizations, institutes and individuals.

Linux is a Unix variant developed by Linus Torvalds and others, and released under General Public License (GPL), meaning it can be distributed, used and expanded free of charge.

Linux Red Hat was a commercial Linux system packaged with an easy-to-use interface and technical support. Copyright and patent problems prevented all Linux features being included, but the company has gone on be a major supplier of open source software and cloud computing.

Questions

1. What is an operating system, and what are its common functions?
2. Describe four popular operating systems.
3. What are the advantages and disadvantages of open source operating systems?

Sources and Further Reading

1. List of operating systems. Wikipedia. A good listing, each listing being linked through to a full page description.
2. Operating Systems. Computer Hope. A short listing of the most popular systems, with link-throughs to specific features and 'how to' details.
3. Compare Windows. Microsoft. Listing of Windows 7 advantages over Windows Vista.
4. Performance showdown: Windows 7 vs. Snow Leopard by Dong Ngo. CNet. October 2009.
5. Unix: History and Timeline. Unix.Org. Detailed history: much else on site.
6. Why Red Hat? Red Hat. Company site with promotional articles.