|
|
|
|
UNIX System V
|
| |
|
| |
Unix System V, commonly abbreviated SysV (and usually pronounced — though rarely written — as "System 5"), is one of the versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, termed Releases 1, 2, 3 and 4. System V Release 4, or SVR4, was the most successful version, being the result of an effort, marketed as Unix System Unification, which solicited the collaboration of the major Unix vendors.
Discussion
Ask a question about 'UNIX System V' Start a new discussion about 'UNIX System V' Answer questions from other users |
Encyclopedia
Unix System V, commonly abbreviated SysV (and usually pronounced — though rarely written — as "System 5"), is one of the versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, termed Releases 1, 2, 3 and 4. System V Release 4, or SVR4, was the most successful version, being the result of an effort, marketed as Unix System Unification, which solicited the collaboration of the major Unix vendors. It was the source of several commercial common Unix features.
While AT&T sold their own hardware that ran System V (see AT&T Computer Systems), most customers ran a version from a reseller, based on AT&T's reference implementation. The most widely used versions of System V today are IBM's AIX, based on System V Release 3, and Sun's Solaris and HP's HP-UX, both based on System V Release 4. Other popular SysV derivatives include Dell SVR4 and Bull SVR4.
System V was an enhancement over AT&T's first commercial Unix called System III (there was never an outside release of System IV). Traditionally, System V has been considered one of the two major "flavors" of UNIX, the other being BSD. However, with the advent of Unix-like systems developed from neither code base, such as Linux and QNX, this generalization is not as accurate as it once was, and in any case standardisation efforts such as POSIX are tending to reduce the differences between implementations.
During the period of the Unix wars System V was known for being the primary choice of manufacturers of large multiuser systems, in opposition to BSD's dominance of desktop workstations.
SVR1
The first version of System V (also called System V.0 or System V Release 1, SVR1) was released in 1983. Developed by AT&T's UNIX Support Group (USG), it was based on the Bell Labs internal USG UNIX 5.0. System V also included features such as the vi editor and curses from the Berkeley Software Distribution of UNIX developed at the University of California, Berkeley (UCB); it also improved performance by adding buffer and inode caches. System V ran on the DEC VAX and PDP-11 machines. It also added support for inter-process communication using messages, semaphores, and shared memory.
SVR2
System V Release 2 was released in 1984. It added shell functions and the SVID. New kernel features included record and file locking, demand paging, and copy on write.
The concept of the "porting base" was formalized, and the DEC VAX 11/780 was named for this Release. The "porting base" is the so-called original version of a Release, from which all porting efforts for other machines emanate. Maurice J. Bach's The Design of the UNIX Operating System is the definitive description of the System V Release 2 kernel.
Apple Computer's A/UX operating system was based on this release (later versions had many extensions from SVR3, SVR4, and BSD), although it was heavily integrated with the Macintosh Toolbox. The first release of HP-UX was also an SVR2 derivative.
SVR3
System V Release 3 was released in 1986.
It included STREAMS, the Remote File System (RFS), the File System Switch (FSS) virtual file system mechanism, a restricted form of shared libraries, and the Transport Layer Interface (TLI) network API. The final version was Release 3.2 in 1988, which added binary compatibility to Xenix on Intel platforms; SCO Xenix System V/386 was based upon 3.2. The AT&T 3B2 became the official "porting base". IBM's AIX operating system is an SVR3 derivative.
SVR4
System V Release 4.0 was announced on October 18, 1988 and was released in 1990. A joint project of Unix System Laboratories and Sun Microsystems, it combined technology from Release 3 as well as 4.3BSD, Xenix, and SunOS:
- From BSD: TCP/IP support, sockets, ufs, support for multiple groups, csh
- From SunOS: the virtual file system interface (replacing the one in System V release 3, the "File System Switch"), Network File System (NFS), new virtual memory system including support for memory mapped files, an improved shared library system based on the SunOS 4.x model, the OpenWindows GUI environment, External Data Representation (XDR) and Remote Procedure Calls (RPC)
- From Xenix: x86 device drivers, binary compatibility with Xenix (in the x86 version of System V)
- Other improvements:
The primary platforms for SVR4 were Intel x86 and SPARC; the SPARC version, called Solaris 2 (or, internally, SunOS 5.x), was developed by Sun. The relationship between Sun and AT&T was terminated after the release of SVR4, meaning that later versions of Solaris did not inherit features of later SVR4.x releases. Sun would in 2005 release most of the source code for Solaris 10 (SunOS 5.10) as the open source OpenSolaris project, creating the only open-source (heavily modified) System V implementation available.
Many versions of SVR4 appeared, because of hardware vendors (HP, SGI) adapting it to their platform, and because porting houses (SCO, Microport, ESIX, UHC) sold enhanced and supported x86 versions. SVR4 was even ported to the Amiga as Amiga Unix and Atari as ASV SVR4 Unix 1991.
SVR4.0MP
Built by a consortium of Intel based resellers (including Unisys, ICL and NCR Corporation). It provided a limited multi-processor capability. This allowed operating system calls to be processed from any processor, but interrupt servicing only from a "master" processor.
SVR4.1 ES
Release 4.1 ES (Enhanced Security) added security features and support for synamic loading of kernel modules.
The security features included interfaces required for Orange Book B2 compliance and Access Control Lists.
SVR4.2
Release 4.2, developed in 1992 was based on Release 4.1 ES and added support for the Veritas filesystem.
Again, several versions of SVR4.2 appeared, including Univel (later SCO) UnixWare 1, UHC UnixWare, and Consensys.
SVR4.2MP
Release 4.2MP, completed late 1993, added support for multiprocessing. It was released as UnixWare 2 in 1995.
SVR5
System V Release 5 was developed in 1997 by the Santa Cruz Operation (SCO) as a merger of SCO OpenServer (an SVR3-derivative) and UnixWare, with a focus on large-scale servers.
It was released as SCO UnixWare 7. SCO's successor, The SCO Group also based SCO OpenServer 6 on SVR5, but the codebase is not used by any other manufacturer.
External links
|
| |
|
|
