42-456: The IBM System/360 Model 67 ( S/360-67 ) was an important IBM mainframe model in the late 1960s. Unlike the rest of the S/360 series, it included features to facilitate time-sharing applications, notably a Dynamic Address Translation unit , the "DAT box", to support virtual memory , 32-bit addressing and the 2846 Channel Controller to allow sharing channels between processors. The S/360-67
84-516: A virtual memory architecture using dynamic address translation (DAT) that could be used to implement time-sharing. After a year of negotiations and design studies, IBM agreed to make a one-of-a-kind version of its S/360-65 mainframe computer for the University of Michigan. The S/360-65M would include dynamic address translation (DAT) features that would support virtual memory and allow support for time-sharing. Initially IBM decided not to supply
126-403: A 1966 JACM paper by Arden, Galler, Westervelt, and O'Brien and included both segment and page tables. The Model 67's virtual memory support was very similar to the virtual memory support that eventually became standard on the entire System/370 line. The S/360-67 provided a 24- or 32-bit address space – unlike the strictly 24-bit address space of other S/360 and early S/370 systems, and
168-861: A basic 750 nanosecond magnetic core storage cycle, the same as the S/360-65. The 200 ns cycle time put the S/360-67 in the middle of the S/360 line, between the Model 30 at the low end and the Model 195 at the high end. From 1 to 8 bytes (8 data bits and 1 parity bit per byte) could be read or written to processor storage in a single cycle. A 60-bit parallel adder facilitated handling of long fractions in floating-point operations. An 8-bit serial adder enabled simultaneous execution of floating point exponent arithmetic, and also handled decimal arithmetic and variable field length (VFL) instructions. Four new components were part of
210-439: A fully supported IBM operating system ( VM/370 and today's z/VM ). VP/CSS , based upon CP/CMS, was developed by National CSS to provide commercial time-sharing services. The S/360-67 had an important legacy. After the failure of TSS/360 , IBM was surprised by the blossoming of a time-sharing community on the S/360-67 platform ( CP/CMS , MTS , MUSIC ). A large number of commercial, academic, and service bureau sites installed
252-919: A lawsuit by IBM. The primary operating systems in use on current IBM mainframes include z/OS (which followed MVS/ESA and OS/390 in the OS/360 lineage), z/VM (which followed VM/ESA and VM/XA SP in the CP-40 lineage), z/VSE (which is in the DOS/360 lineage ), z/TPF (a successor of Transaction Processing Facility in the Airlines Control Program lineage), and Linux on IBM Z (e.g., Debian , Red Hat Enterprise Linux , SUSE Linux Enterprise Server ). Some systems run MUSIC/SP , as well as UTS (Mainframe UNIX) . In October 2008, Sine Nomine Associates introduced OpenSolaris on System z ; it has since been discontinued. Current IBM mainframes run all
294-448: A new time-sharing operating system called IBM Time Sharing System (TSS/360) for delivery at roughly the same time as the first model S/360-67. The first S/360-67 was shipped in May 1966. The S/360-67 was withdrawn on March 15, 1977. Before the announcement of the Model 67, IBM had announced models 64 and 66, DAT versions of its 60 and 62 models, but they were almost immediately replaced by
336-445: A page that was not in memory caused a page fault , which in turn could be intercepted and processed by an operating system interrupt handler . The S/360-67's virtual memory system was capable of meeting three distinct goals: The first goal removed (for decades, at least) a crushing limitation of earlier machines: running out of physical storage. The second enabled substantial improvements in security and reliability. The third enabled
378-414: A time-sharing operating system for the new machine. As other organizations heard about the project they were intrigued by the time-sharing idea and expressed interest in ordering the modified IBM S/360 series machines. With this demonstrated interest IBM changed the computer's model number to S/360-67 and made it a supported product. When IBM realized there was a market for time-sharing, it agreed to develop
420-620: A time-sharing operating system project that was canceled in 1971 (having also been canceled in 1968, but reprieved in 1969). IBM subsequently modified TSS/360 and offered the TSS/370 PRPQ for three releases before cancelling it. IBM's failure to deliver TSS/360 as promised opened the door for others to develop operating systems that would use the unique features of the S/360-67 MTS, the Michigan Terminal System ,
462-422: A time. Later, IBM provided compilers for the newly developed higher-level programming languages Fortran , COMTRAN and later COBOL . The first operating systems for IBM computers were written by IBM customers who did not wish to have their very expensive machines (US$ 2M in the mid-1950s) sitting idle while operators set up jobs manually. These first operating systems were essentially scheduled work queues. It
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#1732798747850504-475: Is generally thought the first operating system used for real work was GM-NAA I/O , produced by General Motors ' Research division in 1956. IBM enhanced one of GM-NAA I/O's successors, the SHARE Operating System , and provided it to customers under the name IBSYS . As software became more complex and important, the cost of supporting it on so many different designs became burdensome, and this
546-453: Is often referred to as lazy loading , as only those pages demanded by the process are swapped from secondary storage to main memory . Contrast this to pure swapping, where all memory for a process is swapped from secondary storage to main memory when the process starts up or resumes execution. Commonly, to achieve this process a memory management unit is used. The memory management unit maps logical memory to physical memory . Entries in
588-399: The 31-bit address space of S/370-XA available on later S/370s. The S/360-67 virtual address space was divided into pages (of 4096 bytes) grouped into segments (of 1 million bytes); pages were dynamically mapped onto the processor's real memory. These S/360-67 features plus reference and change bits as part of the storage key enabled operating systems to implement demand paging : referencing
630-577: The 360 and was mostly programmed in Fortran , which was relatively easy to adapt to larger machines when necessary. IBM also introduced smaller machines after S/360. These included: Midrange computer is a designation used by IBM for a class of computer systems which fall in between mainframes and microcomputers. IBM announced the System/360 (S/360) line of mainframes in April 1964. The System/360
672-399: The 67 at the same time that the 60 and 62 were replaced by the 65. IBM announced the S/360-67 in its August 16, 1965 "blue letters" (a standard mechanism used by IBM to make product announcements). IBM stated that: The S/360-67 design added a component for implementing virtual memory, the "DAT box" (Dynamic Address Translation box). DAT on the 360/67 was based on the architecture outlined in
714-521: The IBM System/360 model 67: A half-duplex system could be upgraded in the field to a duplex system by adding one IBM 2067-2 processor and the third IBM 2365-12 Processor Storage, unless the half-duplex system already had three or more. The half-duplex and duplex configurations were called the IBM System/360 model 67–2. When the S/360-67 was announced in August 1965, IBM also announced TSS/360 ,
756-501: The S/360-67: These components, together with the 2365 Processor Storage Model 2, 2860 Selector Channel, 2870 Multiplexer Channel, and other System/360 control units and devices were available for use with the S/360-67. Note that while Carnegie Tech had a 360/67 with an IBM 2361 LCS, that option was not listed in the price book and may not have worked in a duplex configuration. Three basic configurations were available for
798-505: The S/370 series, a move seen by many as a vindication of work done on the S/360-67 project; the microcode in the 370/145 was updated to use the associative memory for virtual address translation. The survival and success of IBM's VM family, and of virtualization technology in general, also owe much to the S/360-67. In 2010, in the technical description of its latest mainframe, the z196 , IBM stated that its software virtualization started with
840-513: The System/360 model 67. IBM mainframe IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the computer market with the 7000 series and the later System/360 , followed by the System/370 . Current mainframe computers in IBM's line of business computers are developments of the basic design of the System/360. From 1952 into
882-403: The System/360. However, models were upward compatible and most were also downward compatible. The System/360 was also the first computer in wide use to include dedicated hardware provisions for the use of operating systems . Among these were supervisor and application mode programs and instructions, as well as built-in memory protection facilities. Hardware memory protection was provided to protect
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#1732798747850924-595: The first System/370 models; the OS/VS1 variant of OS/360 MFT, the OS/VS2 (SVS) variant of OS/360 MVT, and the DOS/VS variant of DOS/360 were introduced to use the virtual memory capabilities, followed by MVS , which, unlike the earlier virtual-memory operating systems, ran separate programs in separate address spaces, rather than running all programs in a single virtual address space. The virtual memory capabilities also allowed
966-423: The freely available Hercules , which runs under Linux , FreeBSD , Solaris , macOS and Microsoft Windows . IBM offers an emulator called zPDT (System z Personal Development Tool) which runs on Linux on x86-64 machines. Demand paging In computer operating systems , demand paging (as opposed to anticipatory paging ) is a method of virtual memory management. In a system that uses demand paging,
1008-400: The implementation of true virtual machines . Contemporary documents make it clear that full hardware virtualization and virtual machines were not original design goals for the S/360-67. The S/360-67 included the following extensions in addition to the standard and optional features available on all S/360 systems: The S/360-67 operated with a basic internal cycle time of 200 nanoseconds and
1050-569: The importance of time-sharing and the need to support it. A paper titled Program and Addressing Structure in a Time-Sharing Environment by Bruce Arden , Bernard Galler , Frank Westervelt (all associate directors at the University of Michigan's academic Computing Center), and Tom O'Brian building upon some basic ideas developed at the Massachusetts Institute of Technology (MIT) was published in January 1966. The paper outlined
1092-910: The late 1960s, IBM manufactured and marketed several large computer models, known as the IBM 700/7000 series . The first-generation 700s were based on vacuum tubes , while the later, second-generation 7000s used transistors . These machines established IBM's dominance in electronic data processing ("EDP"). IBM had two model categories: one (701, 704, 709, 7030, 7090, 7094, 7040, 7044) for engineering and scientific use, and one (702, 705, 705-II, 705-III, 7080, 7070, 7072, 7074, 7010) for commercial or data processing use. The two categories, scientific and commercial, generally used common peripherals but had completely different instruction sets , and there were incompatibilities even within each category. IBM initially sold its computers without any software, expecting customers to write their own; programs were manually initiated, one at
1134-505: The later System/370 was the ability to switch to emulation mode and back under operating system control. Operating systems for the System/360 family included OS/360 (with PCP, MFT, and MVT ), BOS/360 , TOS/360 , and DOS/360 . The System/360 later evolved into the System/370 , the System/390 , and the 64-bit zSeries, System z, and zEnterprise machines. System/370 introduced virtual memory capabilities in all models other than
1176-469: The major enterprise transaction processing environments and databases , including CICS , IMS , WebSphere Application Server, IBM Db2 , and Oracle . In many cases these software subsystems can run on more than one mainframe operating system. There are software-based emulators for the System/370, System/390, and System z hardware, including FLEX-ES , which runs under UnixWare or Linux , and
1218-405: The mid-1960s a number of organizations were interested in offering interactive computing services using time-sharing . At that time the work that computers could perform was limited by their lack of real memory storage capacity. When IBM introduced its System/360 family of computers in the mid-1960s, it did not provide a solution for this limitation and within IBM there were conflicting views about
1260-477: The number of CPs). There are other supporting processors typically installed inside mainframes such as cryptographic accelerators ( CryptoExpress ), the OSA-Express networking processor, and FICON Express disk I/O processors. Software to allow users to run "traditional" workloads on zIIPs and zAAPs was briefly marketed by Neon Enterprise Software as "zPrime" but was withdrawn from the market in 2011 after
1302-511: The operating system copies a disk page into physical memory only when an attempt is made to access it and that page is not already in memory ( i.e. , if a page fault occurs). It follows that a process begins execution with none of its pages in physical memory, and triggers many page faults until most of its working set of pages are present in physical memory. This is an example of a lazy loading technique. Demand paging only brings pages into memory when an executing process demands them. This
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1344-411: The operating system from the user programs (tasks) and user tasks from each other. The new machine also had a larger address space than the older mainframes, 24 bits addressing 8-bit bytes vs. a typical 18 bits addressing 36-bit words. The smaller models in the System/360 line (e.g. the 360/30) were intended to replace the 1400 series while providing an easier upgrade path to the larger 360s. To smooth
1386-413: The smaller machines to the mainframes because so much software had to be rewritten. The 7010 was introduced in 1962 as a mainframe-sized 1410. The later Systems 360 and 370 could emulate the 1400 machines. A desk-size machine with a different instruction set, the IBM 1130 , was released concurrently with the System/360 to address the niche occupied by the 1620. It used the same EBCDIC character encoding as
1428-461: The system to support virtual machines ; the VM/370 hypervisor would run one or more virtual machines running either standard System/360 or System/370 operating systems or the single-user Conversational Monitor System (CMS). A time-sharing VM system could run multiple virtual machines, one per user, with each virtual machine running an instance of CMS. The IBM Z family, introduced in 2000 with
1470-461: The system. By taking advantage of IBM's lukewarm support for time-sharing, and by sharing information and resources (including source code modifications), they built and supported a generation of time-sharing centers. The unique features of the S/360-67 were initially not carried into IBM's next product series, the System/370 , although the 370/145 had an associative memory that appeared more useful for paging than for its ostensible purpose. This
1512-414: The transition from the second generation to the new line, IBM used the 360's microprogramming capability to emulate the more popular older models. Thus 360/30s with this added cost feature could run 1401 programs and the larger 360/65s could run 7094 programs. To run old programs, the 360 had to be halted and restarted in emulation mode. Many customers kept using their old software and one of the features of
1554-487: The z900, supports z/Architecture , which extends the architecture used by the System/390 mainframes to 64 bits. The different processors on current IBM mainframes are: These are essentially identical, but distinguished for software cost control: all but CP are slightly restricted such they cannot be used to run arbitrary operating systems, and thus do not count in software licensing costs (which are typically based on
1596-474: Was a single series of compatible models for both commercial and scientific use. The number " 360 " suggested a "360 degree ," or "all-around" computer system. System/360 incorporated features which had previously been present on only either the commercial line (such as decimal arithmetic and byte addressing) or the engineering and scientific line (such as floating-point arithmetic ). Some of the arithmetic units and addressing features were optional on some models of
1638-583: Was largely fallout from a bitter and highly visible political battle within IBM over the merits of time-sharing versus batch processing . Initially at least, time-sharing lost. However, IBM faced increasing customer demand for time-sharing and virtual memory capabilities. IBM also could not ignore the large number of S/360-67 time-sharing installations – including the new industry of time-sharing vendors, such as National CSS and Interactive Data Corporation (IDC), that were quickly achieving commercial success. In 1972, IBM added virtual memory features to
1680-556: Was one of the factors which led IBM to develop System/360 and its operating systems. The second generation (transistor-based) products were a mainstay of IBM's business and IBM continued to make them for several years after the introduction of the System/360. (Some IBM 7094s remained in service into the 1980s.) Prior to System/360, IBM also sold computers smaller in scale that were not considered mainframes, though they were still bulky and expensive by modern standards. These included: IBM had difficulty getting customers to upgrade from
1722-626: Was otherwise compatible with the rest of the S/360 series. The S/360-67 was intended to satisfy the needs of key time-sharing customers, notably MIT (where Project MAC had become a notorious IBM sales failure), the University of Michigan , General Motors , Bell Labs , Princeton University , the Carnegie Institute of Technology (later Carnegie Mellon University ), and the Naval Postgraduate School . In
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1764-621: Was the time-sharing operating system developed at the University of Michigan and first used on the Model 67 in January 1967. Virtual memory support was added to MTS in October 1967. Multi-processor support for a duplex S/360-67 was added in October 1968. CP/CMS was the first virtual machine operating system. Developed at IBM's Cambridge Scientific Center (CSC) near MIT. CP/CMS was essentially an unsupported research system, built away from IBM's mainstream product organizations, with active involvement of outside researchers. Over time it evolved into
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