Early operating systems were very diverse, with each vendor or customer producing one or more operating systems specific to their particular mainframe computer. Every operating system, even from the same vendor, could have radically different models of commands, operating procedures, and such facilities as debugging aids. Typically, each time the manufacturer brought out a new machine, there would be a new operating system, and most applications would have to be manually adjusted, recompiled, and retested.
Systems on IBM hardware
Main article: History of IBM mainframe operating systems
The state of affairs continued until the 1960s when IBM, already a leading hardware vendor, stopped work on existing systems and put all its effort into developing the System/360 series of machines, all of which used the sameinstruction and input/output architecture. IBM intended to develop a single operating system for the new hardware, the OS/360. The problems encountered in the development of the OS/360 are legendary, and are described by Fred Brooks in The Mythical Man-Month—a book that has become a classic of software engineering. Because of performance differences across the hardware range and delays with software development, a whole family of operating systems was introduced instead of a single OS/360.[5][6]
IBM wound up releasing a series of stop-gaps followed by two longer-lived operating systems:
- OS/360 for mid-range and large systems. This was available in three system generation options:
- PCP for early users and for those without the resources for multiprogramming.
- MFT for mid-range systems, replaced by MFT-II in OS/360 Release 15/16. This had one successor, OS/VS1, which was discontinued in the 1980s.
- MVT for large systems. This was similar in most ways to PCP and MFT (most programs could be ported among the three without being re-compiled), but has more sophisticated memory management and a time-sharing facility,TSO. MVT had several successors including the current z/OS.
- DOS/360 for small System/360 models had several successors including the current z/VSE. It was significantly different from OS/360.
IBM maintained full compatibility with the past, so that programs developed in the sixties can still run under z/VSE (if developed for DOS/360) or z/OS (if developed for MFT or MVT) with no change.
IBM also developed TSS/360, a time-sharing system for the System/360 Model 67. Overcompensating for their perceived importance of developing a timeshare system, they set hundreds of developers to work on the project. They ended up with a bloated, buggy project that took as long to boot as it did to crash, and ended the project without releasing it.[7]
Several operating systems for the IBM S/360 and S/370 architectures were developed by third parties, including the Michigan Terminal System (MTS) andMUSIC/SP.
Other mainframe operating systems
Control Data Corporation developed the SCOPE operating systems[NB 1] in the 1960s, for batch processing and later developed the MACE operating system for time sharing, which was the basis for the later Kronos. In cooperation with the University of Minnesota, the Kronos and later the NOS operating systems were developed during the 1970s, which supported simultaneous batch and timesharing use. Like many commercial timesharing systems, its interface was an extension of the DTSS time sharing system, one of the pioneering efforts in timesharing and programming languages.
In the late 1970s, Control Data and the University of Illinois developed thePLATO system, which used plasma panel displays and long-distance time sharing networks. PLATO was remarkably innovative for its time; the shared memory model of PLATO's TUTOR programming language allowed applications such as real-time chat and multi-user graphical games.
For the UNIVAC 1107, UNIVAC, the first commercial computer manufacturer, produced the EXEC I operating system, and Computer Sciences Corporationdeveloped the EXEC II operating system and delivered it to UNIVAC. EXEC II was ported to the UNIVAC 1108. Later, UNIVAC developed the EXEC 8 operating system for the 1108; it was the basis for operating systems for later members of the family. Like all early mainframe systems, EXEC I and EXEC II were a batch-oriented system that managed magnetic drums, disks, card readers and line printers; EXEC 8 supported both batch processing and on-line transaction processing. In the 1970s, UNIVAC produced the Real-Time Basic (RTB) system to support large-scale time sharing, also patterned after the Dartmouth BASICsystem.
Burroughs Corporation introduced the B5000 in 1961 with the MCP (Master Control Program) operating system. The B5000 was a stack machine designed to exclusively support high-level languages, with no software, not even at the lowest level of the operating system, being written directly in machine languageor assembly language; the MCP was the first[citation needed] OS to be written entirely in a high-level language - ESPOL, a dialect of ALGOL 60 - although ESPOL had specialized statements for each "syllable"[8] in the B5000 instruction set. MCP also introduced many other ground-breaking innovations, such as being one of[NB 2] the first commercial implementations of virtual memory. The rewrite of MCP for the B6500 is still in use today in the Unisys ClearPath/MCP line of computers.
GE introduced the GE-600 series with the General Electric Comprehensive Operating Supervisor (GECOS) operating system in 1962. After Honeywellacquired GE's computer business, it was renamed to General Comprehensive Operating System (GCOS). Honeywell expanded the use of the GCOS name to cover all its operating systems in the 1970s, though many of its computers had nothing in common with the earlier GE 600 series and their operating systems were not derived from the original GECOS.
Project MAC at MIT, working with GE and Bell Labs, developed Multics, which introduced the concept of ringed security privilege levels.
Digital Equipment Corporation developed TOPS-10 for its PDP-10 line of 36-bit computers in 1967. Before the widespread use of Unix, TOPS-10 was a particularly popular system in universities, and in the early ARPANETcommunity. Bolt, Beranek, and Newman developed TENEX for a modified PDP-10 that supported demand paging; this was another popular system in the research and ARPANET communities, and was later developed by DEC intoTOPS-20.
Scientific Data Systems/Xerox Data Systems developed several operating systems for the Sigma series of computers, such as the Basic Control Monitor (BCM), Batch Processing Monitor (BPM), and Basic Time-Sharing Monitor (BTM). Later, BPM and BTM were succeeded by the Universal Time-Sharing System (UTS); it was designed to provide multi-programming services for online (interactive) user programs in addition to batch-mode production jobs, It was succeeded by the CP-V operating system, which combined UTS with the heavily batch-oriented Xerox Operating System (XOS).
source wikipedia
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