IBM mainframe

Last updated

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.

Contents

First and second generation

IBM 704 mainframe at NACA in 1957 IBM Electronic Data Processing Machine - GPN-2000-001881.jpg
IBM 704 mainframe at NACA in 1957

From 1952 into 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 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 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. [1] [2] As software became more complex and important, the cost of supporting it on so many different designs became burdensome, and this was one of the factors which led IBM to develop System/360 and its operating systems. [3]

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.)

Smaller machines

IBM 1401 undergoing restoration at the Computer History Museum IBM 1401 signal tracing at CHM.jpg
IBM 1401 undergoing restoration at the Computer History Museum

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 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 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 System/360

IBM System/360 Model 50 IBM system 360-50 console - MfK Bern.jpg
IBM System/360 Model 50

IBM announced the System/360 (S/360) line of mainframes in April 1964. [4] The System/360 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 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 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 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 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 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 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.

Today's systems

IBM System z800 Z800 2066 JKU.jpeg
IBM System z800

The IBM Z family, introduced in 2000 with the z900, supports z/Architecture, which extends the architecture used by the System/390 mainframes to 64 bits.

Processor units

The different processors on current IBM mainframes are:

These are essentially identical, but distinguished for software cost control: all but CP are slightly restricted [lower-alpha 1] such they cannot be used to run arbitrary operating systems, and thus do not count in software licensing costs (which are typically based on the number of CPs). [5] 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 a lawsuit by IBM. [6]

Operating systems

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.

Middleware

Current IBM mainframes run all 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.

Emulators

There are software-based emulators for the System/370, System/390, and System z hardware, including FLEX-ES, which runs under UnixWare or Linux, [7] and 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. [8]

See also

Notes

  1. ↑ All supported IBM operating systems test the type of processor they are running on and restrict usage in accordance with license terms.

Related Research Articles

<span class="mw-page-title-main">MVS</span> Operating system for IBM mainframes

Multiple Virtual Storage, more commonly called MVS, is the most commonly used operating system on the System/370, System/390 and IBM Z IBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unrelated to IBM's other mainframe operating system lines, e.g., VSE, VM, TPF.

<span class="mw-page-title-main">IBM System/360</span> IBM mainframe computer family (1964–1977)

The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applications and a complete range of applications from small to large. The design distinguished between architecture and implementation, allowing IBM to release a suite of compatible designs at different prices. All but the only partially compatible Model 44 and the most expensive systems use microcode to implement the instruction set, featuring 8-bit byte addressing and fixed point binary, fixed point decimal and hexadecimal floating-point calculations.

<span class="mw-page-title-main">Virtual memory</span> Computer memory management technique

In computing, virtual memory, or virtual storage, is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very large (main) memory".

<span class="mw-page-title-main">VSE (operating system)</span> Operating system

VSEn is an operating system for IBM mainframe computers, the latest one in the DOS/360 lineage, which originated in 1965. It is less common than z/OS and is mostly used on smaller machines.

<span class="mw-page-title-main">Hercules (emulator)</span> Multi-platform emulator for mainframe software

Hercules is a computer emulator allowing software written for IBM mainframe computers and for plug compatible mainframes to run on other types of computer hardware, notably on low-cost personal computers. Development started in 1999 by Roger Bowler, a mainframe systems programmer.

<span class="mw-page-title-main">History of operating systems</span> Aspect of computing history

Computer operating systems (OSes) provide a set of functions needed and used by most application programs on a computer, and the links needed to control and synchronize computer hardware. On the first computers, with no operating system, every program needed the full hardware specification to run correctly and perform standard tasks, and its own drivers for peripheral devices like printers and punched paper card readers. The growing complexity of hardware and application programs eventually made operating systems a necessity for everyday use.

<span class="mw-page-title-main">IBM System/370</span> Family of mainframe computers 1970–1990

The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement.

<span class="mw-page-title-main">64-bit computing</span> Computer architecture bit width

In computer architecture, 64-bit integers, memory addresses, or other data units are those that are 64 bits wide. Also, 64-bit central processing units (CPU) and arithmetic logic units (ALU) are those that are based on processor registers, address buses, or data buses of that size. A computer that uses such a processor is a 64-bit computer.

<span class="mw-page-title-main">VM (operating system)</span> Family of IBM operating systems

VM is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers.

A hypervisor, also known as a virtual machine monitor (VMM) or virtualizer, is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is called a host machine, and each virtual machine is called a guest machine. The hypervisor presents the guest operating systems with a virtual operating platform and manages the execution of the guest operating systems. Unlike an emulator, the guest executes most instructions on the native hardware. Multiple instances of a variety of operating systems may share the virtualized hardware resources: for example, Linux, Windows, and macOS instances can all run on a single physical x86 machine. This contrasts with operating-system–level virtualization, where all instances must share a single kernel, though the guest operating systems can differ in user space, such as different Linux distributions with the same kernel.

z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit complex instruction set computer (CISC) instruction set architecture, implemented by its mainframe computers. IBM introduced its first z/Architecture-based system, the z900, in late 2000. Later z/Architecture systems include the IBM z800, z990, z890, System z9, System z10, zEnterprise 196, zEnterprise 114, zEC12, zBC12, z13, z14, z15 and z16.

A logical partition (LPAR) is a subset of a computer's hardware resources, virtualized as a separate computer. In effect, a physical machine can be partitioned into multiple logical partitions, each hosting a separate instance of an operating system.

Since the rise of the personal computer in the 1980s, IBM and other vendors have created PC-based IBM mainframe-compatible systems which are compatible with the larger IBM mainframe computers. For a period of time PC-based mainframe-compatible systems had a lower price and did not require as much electricity or floor space. However, they sacrificed performance and were not as dependable as mainframe-class hardware. These products have been popular with mainframe developers, in education and training settings, for very small companies with non-critical processing, and in certain disaster relief roles.

IBM Z Family of mainframe computers

IBM Z is a family name used by IBM for all of its z/Architecture mainframe computers. In July 2017, with another generation of products, the official family was changed to IBM Z from IBM z Systems; the IBM Z family now includes the newest model, the IBM z16, as well as the z15, the z14, and the z13, the IBM zEnterprise models, the IBM System z10 models, the IBM System z9 models and IBM eServer zSeries models.

The IBM Basic assembly language and successors is a series of assembly languages and assemblers made for the IBM System/360 mainframe system and its successors through the IBM Z.

The following is a timeline of virtualization development. In computing, virtualization is the use of a computer to simulate another computer. Through virtualization, a host simulates a guest by exposing virtual hardware devices, which may be done through software or by allowing access to a physical device connected to the machine.

The history of IBM mainframe operating systems is significant within the history of mainframe operating systems, because of IBM's long-standing position as the world's largest hardware supplier of mainframe computers. IBM mainframes run operating systems supplied by IBM and by third parties.

Linux on IBM Z or Linux on zSystems is the collective term for the Linux operating system compiled to run on IBM mainframes, especially IBM Z / IBM zSystems and IBM LinuxONE servers. Similar terms which imply the same meaning are Linux/390, Linux/390x, etc. The three Linux distributions certified for usage on the IBM Z hardware platform are Red Hat Enterprise Linux, SUSE Linux Enterprise Server, and Ubuntu.

In computing, a system virtual machine is a virtual machine (VM) that provides a complete system platform and supports the execution of a complete operating system (OS). These usually emulate an existing architecture, and are built with the purpose of either providing a platform to run programs where the real hardware is not available for use, or of having multiple instances of virtual machines leading to more efficient use of computing resources, both in terms of energy consumption and cost effectiveness, or both. A VM was originally defined by Popek and Goldberg as "an efficient, isolated duplicate of a real machine".

References

  1. ↑ "IBM 7090/94 IBSYS Operating System". Archived from the original on April 24, 2021.
  2. ↑ Gray, George (March 1999). "EXEC II". Unisys History Newsletter. 1 (3). Archived from the original on August 9, 2017.
  3. ↑ Chuck Boyer. "The 360 Revolution" (PDF). IBM. Archived from the original on July 1, 2023. Retrieved December 22, 2020.
  4. ↑ "IBM Archives: System/360 Announcement". IBM . January 23, 2003. Archived from the original on January 2, 2021. Retrieved December 22, 2020.
  5. ↑ IBM corp. (2005). "Mainframe concepts (page 31)" (PDF). Archived (PDF) from the original on July 8, 2012. Retrieved May 5, 2012.
  6. ↑ Radding, Alan (June 6, 2011). "Bye bye zPrime on System z". DancingDinosaur. Archived from the original on June 30, 2012. Retrieved May 5, 2012.
  7. ↑ "Technical Overview: FLEX-ES". Archived from the original on May 18, 2015. Retrieved May 8, 2015.
  8. ↑ "IBM System z Personal Development Tool". IBM. Archived from the original on March 4, 2016. Retrieved January 27, 2016.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.