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|Written in||SPL, C|
|Latest release||BS2000/OSD v10.0 / 2016|
|Marketing target||Mainframe computers|
|Platforms||Siemens 7.700 and 7.500 mainframes, /370, MIPS, SPARC, x86 - Fujitsu Technology Solutions S-Series|
|Official website||BS2000 Mainframes|
BS2000 (renamed BS2000/OSD in 1992) is a mainframe computer operating system developed in the 1970s by Siemens (Data Processing Department EDV) and from early 2000s onward by Fujitsu Technology Solutions.
Unlike other mainframe systems, BS2000/OSD provides exactly the same user and programming interface in all operating modes (batch, interactive and online transaction processing) and regardless of whether it is running natively or as a guest system in a virtual machine. This uniformity of the user interface and the entire BS2000 software configuration makes administration and automation particularly easy.
It's mainly used in Germany with a share of 83%, United Kingdom(8%), Belgium(4.8%) and other European countries(4.2%). 
BS2000/OSD had its roots in the Time Sharing Operating System (TSOS) first developed by RCA for the /46 model of the Spectra/70 series, a computer family of the late 1960s related in its architecture to IBM’s /360 series. It was an early operating systems which used virtual addressing and a segregated address space for the programs of different users. From the outset TSOS also allowed data peripherals to be accessed only via record- or block-oriented file interfaces, thereby preventing the necessity to implement device dependencies in user programs. The same operating system was also sold to Sperry Univac when it bought most of RCA's computer division. Univac's "fork" of TSOS would become VS/9, which used many of the same concepts.
In 1973 BS2000 V1.0 was a port of the TSOS operating system to models of the Siemens system 7.700 In June 1975, Siemens shipped the enhanced BS2000 V2.0 version of the TSOS operating system for the models of the Siemens 7.700 mainframe series for the first time under the name BS2000. This first version supported disk paging and three different operating modes in the same system: interactive dialog, batch, and transaction mode, a precursor of online transaction processing. In 1977 the TRANSDATA communication system used computer networking.
The 1978 multiprocessor technology was introduced. The operating system had the ability to cope with a processor failure. At the same time the new technology considerably extended the performance range of the system. In 1979 a transaction processing monitor, the Universal Transaction Monitor (UTM), was introduced, providing support for online transaction processing as an additional operating mode.
In 1980 Siemens introduced the system 7.500 hardware family, ranging from desk size models for use in office environments to large models with water cooling. In 1987 BS2000 V9.0 was ported to the /370 architecture supported 2GB address spaces, 512 processes and the XS channel system (Dynamic Channel Subsystem). BS2000 was subdivided into subsystems decoupled from one another.
With the advent of the VM2000 virtual machine in 1990, multiple BS2000 systems, of the same or different versions, can run in parallel on the same computer. The hierarchical storage management system HSMS swapped out infrequently used data to cheaper storage media. When the data is needed again, it is restored to high-speed access media. The MAREN tape archiving system supported robot systems. In 1991 the Security evaluation to F2/Q3 was completed. From 1992 through 1995 BS2000/OSD V1.0 was made open to application software and was renamed BS2000/OSD (Open Server Dimension). Full support of the XPG4 standard was achieved in 1995 after the porting of the POSIX interfaces in 1992. In 1996 BS2000/OSD was ported to the MIPS architecture. Although the operating system ran on different hardware architectures (S servers with /390 architecture and SR2000 servers for the MIPS architecture), applications produced for /390 can be used on computers based on MIPS architecture without recompilation due an emulation layer for legacy code. In 1997 WebTransactions allowed applications to use the Internet. In 1999 BS2000/OSD was the first operating system to be awarded Internet Branding by The Open Group.
In 2002 BS2000/OSD was ported to the SPARC architecture, leading to the Fujitsu Siemens Computers’ SX server line. In 2004 support for storage area networks based on Fibre Channel technology was introduced. In 2005 the mainframe system celebrates its 30th anniversary in July. In 2006, BS2000/OSD V7.0 introduced support for new server generations, Unicode support, and improved SAN integration. In 2007 BS2000/OSD version 7.0 was released. This included snap and clone functionality of the EMC Symmetrix DMX storage systems for BS2000 files and disks, online provisioning of disks, and dynamic priority control of I/O. In 2008 BS2000/OSD was ported to the x86 architecture, and the SQ server line was introduced. In 2012 BS2000/OSD version 9.0 was released. Pilot release of version 10.0 started in November 2014, full release is planned for April 2015.
- BS2000/OSD Strategy, March 2010
- https://sp.ts.fujitsu.com/dmsp/Publications/public/BS2Freigabeseminar-01-News-at-BS2000.pdf BS2000 – Geschäft und Strategie
- Präsentation: BS2000/OSD V8.0
- BS2000/OSD V8.0A Release Notice November 2010