- IBM mainframe
IBM mainframes, though perceived as synonymous with
mainframe computers in general due to their marketshare, are now technically and specificallyIBM 's line of business computers that can all trace their design evolution to the IBMSystem/360 .First and second generation
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 onvacuum tube s, while the later, second-generation 7000s usedtransistor s. These machines established IBM's dominance in electronic data processing. IBM had two model categories: one (701, 704, 709, 7090, 7040) for engineering and scientific use, and one (702, 705, 7080, 7070, 7010) for commercial or data processing use. The two categories, scientific and commercial, generally used common peripherals but had completely differentinstruction set s, 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 language sFortran andCOBOL . The first operating systems for IBM computers were written by IBM customers who did not wish to have their very expensive machines ($2M USD in the mid-1950s) sitting idle while operators set up jobs manually, and so they wanted a mechanism for maintaining a queue of jobs. It is generally thought that the first operating system used for real work wasGM-NAA I/O , produced byGeneral Motors ' Research division in 1956. [http://www.bozemanlug.org/talks/linux_history.html A Brief History of Linux] ] IBM enhanced one of GM-NAA I/O's successors and provided it to customers under the nameIBSYS . [http://www.frobenius.com/ibsys.htm IBM 7090/94 IBSYS Operating System] ] Cite journal
author=Gray, G.
date=1999
title=EXEC II
periodical=Unisys History Newsletter
volume=1
issue=3
url=http://www.cc.gatech.edu/~randy/folklore/v1n3.html] 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 developSystem/360 and its operating systems.Chuck Boyer, [http://www-306.ibm.com/software/os/zseries/pdf/360Revolution_0406.pdf "The 360 Revolution"] ]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 7094 s remained in service into the 1980s.)maller machines
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 650 (vacuum tube logic, decimal architecture, business and scientific)
*IBM RAMAC 305 (vacuum tube logic, first computer with disk storage; "see:"Early IBM disk storage )
*IBM 1400 series (business data processing; very successful and many 1400 peripherals were used with the 360s)
*IBM 1620 (decimal architecture, engineering, scientific, and education)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 concurrent with the System/360 to address the 1620s niche. 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."Midrange computer" is a designation used by IBM for a class of computer systems which fall in between mainframes and microcomputers.
IBM System/360
All that changed with the announcement of the System/360 (S/360) in April, 1964 [ [http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PR360.html IBM Archives: System/360 Announcement] ] . 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 technical 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 ofoperating system s. 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 the user tasks from each other.] The new machine also had a largeraddress space than the older mainframes, 24 bits vs. a typical 18 bits.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 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 and its successors included
OS/360 (with PCP, MFT, and MVT), BOS, TOS, DOS, and SVS. The original OS/360 and earlyMVS andVM/CMS versions did not include a copyright literal in the object code and therefore not protected by U.S. Copyright Laws and are available for free use.The System/360 later evolved into the
System/370 , theSystem/390 , the zSeries, theSystem z9 , and today'sSystem z10 .Today's Systems
Processor units
The different processors on a current IBM mainframes are:
*CP, Central Processor: general-purpose processor
*IFL,Integrated Facility for Linux : dedicated toLinux OSes (optionally underz/VM )
*ICF, IntegratedCoupling Facility : designed to supportParallel Sysplex operations
*SAP, System Assist Processor: designed to handle various system accounting, management, andI/O channel operations
*zAAP , System z9 Application Assist Processor: currently limited to run only Java andXML processing
*zIIP , System z9 Integrated Information Processor: dedicated to run specific workloads includingDB2 ,XML , andIPSec There are other supporting processors typically installed inside mainframes such as
cryptographic accelerators (CryptoExpress ), theOSA-Express networking processor, andFICON Express disk I/O processors.Mainframes in General
Operating Systems
The primary
operating system s in use on current IBM mainframes includez/OS (which followedMVS andOS/390 ),z/VM (previouslyVM/CMS ),z/VSE ,z/TPF , andLinux on zSeries . A few systems runMUSIC/SP andUTS (Mainframe UNIX) . There are software-based emulators for the System/370, System/390, zSeries, and System z9 hardware, includingFLEX-ES and the freely availableHercules emulator which runs underLinux andMicrosoft Windows . As of mid-2007, Sine Nomine Associates expects to introduceOpenSolaris on System z . [ [http://www.sinenomine.net/node/607 http://www.sinenomine.net/node/607] , retrieved September 12, 2007.]Middleware
Current IBM mainframes run all the major enterprise
transaction processing environments anddatabase s, includingCICS , IMS,WebSphere Application Server, DB2, and Oracle. In many cases thesesoftware subsystems can run on more than one mainframe operating system.ee also
*
List of IBM products
*Amdahl Corporation
*IBM midrange computer References
*Prasad, Nallur and Savit, Jeffrey (1994). "IBM Mainframes: Architecture and Design", 2nd ed. McGraw-Hill Osborne Media. ISBN 0-07-050691-4. [Now dated. For details on the significant
64-bit architectural changes, refer to IBM technical publications (seez/Architecture ).]External links
* [http://ibm.com/zseries Official IBM mainframe page (zSeries/z9)]
Notes
Wikimedia Foundation. 2010.