Finally, early operating systems did not provide memory protection for individual processes or the operating system kernel, thus allowing application “bugs” to result in damage to the parts of the operating system and applications loaded into memory.
The poor reliability of early operating systems is (in part) due to the lack of support for these features.
The monolithic design is older and uses a single binary image to provide the resource management and hardware interface functions of the core layer. Some examples of the monolithic design are Linux and Solaris.
A micro-kernel design uses a very small task management component and a suite of modules for all other resource management functions. Windows NT, Windows 2000, Windows XP and Mac OS X are examples of micro-kernel designs.
From the perspective of a system administrator, a BSD derived UNIX has several noteworthy differences from its System V cousins.
The option flags and output format for several programs, are different from their System V counterparts.
BSD UNIXes use a small collection of run control files (e.g. /etc/rc, /etc/rc.local) which each start multiple service daemons.
The BSD UNIX device naming convention for disk and tape drives usually uses a flat directory scheme with a letter, number, letter pattern (e.g. /dev/rz0a) to specify the device driver, device number and partition or density.
Basic terminology and history gives the system administrator the background to take on the tasks she faces.
Understanding some basic terminology aids in the choice of software, operating systems and hardware and forms a common language for broad descriptions of these items and their relation to each other.
The history of the development of UNIX, Windows and Mac OS provides insights into the organization, tools and problems one faces on a particular type of system. An understanding and knowledge of this history allows a system administrator to more rapidly come up to speed when faced with a new system.