PC-based IBM mainframe-compatible systems: Difference between revisions

Revision as of 14:40, 16 January 2021

Latest revision as of 03:09, 19 August 2025

(40 intermediate revisions by 22 users not shown)

Line 1:

{{short description|Type of computer system}}

{{Essay-like|date=July 2020}}

Since the rise of the [[personal computer]] in the 1980s, [[IBM]] and other vendors have created '''PC-based IBM mainframe-compatible mainframessystems''' which are compatible with the larger IBM [[mainframe computer]]s. 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 (such as field insurance adjustment systems for hurricane relief).

==Background==

Line 8 ⟶ 9:

IBM had demonstrated use of a mainframe instruction set in their first desktop computer—the [[IBM 5100]], released in 1975. This product used microcode to execute many of the [[System/370]]'s processor instructions, so that it could run a slightly modified version of IBM's [[APL (programming language)|APL]] mainframe program interpreter.

In 1980 rumors spread of a new IBM personal computer, perhaps a miniaturized version of the 370.<ref name="byte198101">{{cite news | url=https://archive.org/stream/byte-magazine-1981-01/1981_01_BYTE_06-01_Hand-held_Computers#page/n313/mode/2up | title=Interest Group for Possible IBM Computer | work=BYTE | date=January 1981 | accessdate=18 October 2013 | pages=313}}</ref> In 1981 the [[IBM Personal Computer]] appeared, but it was not based on the System 370 architecture. However, IBM did use their new PC platform to create some exotic combinations with additional hardware that could execute S/370 instructions locally.

===Personal Computer XT/370===

In October 1983, IBM announced the IBM Personal Computer XT/370. This was essentially a three-in-one product. It could run [[PC DOS]] locally, it could also act as [[3270]] terminal, and finally—its most important distinguishing feature relative to an [[IBM 3270 PC]]—was that it could execute S/370 instructions locally.{{r|byte1984fall}}

[[File:IBM XT370 board (1).jpg|thumb|IBM XT/370 board and diagnostic diskette]]

The XT/370 was an [[IBM Personal Computer XT]] (System Unit 5160) with three custom 8-bit cards. The processor card (370PC-P),<ref>{{cite web |url=https://priorart.ip.com/IPCOM/000059679# |archive-url=https://web.archive.org/web/20151211060121/http://priorart.ip.com/IPCOM/000059679 |url-status=dead |archive-date=2015-12-11 |title=Implementation of IBM System 370 Via Co-Microprocessors/The Co-Processor... - IPCOM000059679D - IP.com |publisher=Priorartdatabase.com |date= |accessdate=2020-07-23 }}</ref> contained two modified [[Motorola_68000_seriesMotorola 68000 series|Motorola 68000]] chips (which could emulate most S/370 fixed-point instructions and non-floating-point instructions), and an [[Intel 8087|Intel 8087 coprocessor ]] modified to emulate the S/370 floating point instructions. The second card (370PC-M), which connected to the first with a unique card back connector contained 512 [[Kibibyte|KiB]] of memory. The third card (PC3277-EM), was a 3270 terminal emulator required to download system software from the host mainframe. The XT/370 computer booted into DOS, then ran the [[VM (operating system)|VM]]/PC Control Program. The card's memory space added additional system memory, so the first {{val|256 |ul=KiB}} ([[motherboard]]) memory could be used to move data to the {{val|512 |u=KiB}} expansion card. The expansion memory was dual ported, and provided an additional {{val|384 |u=KiB}} to the XT Machine bringing the total RAM on the XT side to {{val|640 |u=KiB}}. The memory arbitrator could bank switch the second 128 KiB bank on the card to other banks, allowing the XT [[Intel 8088]] processor to address all the RAM on the 370PC-M card.<ref name=Mueller92>Scott Mueller ''Upgrading and Repairing PCs, Second Edition'', Que Books, 1992, {{ISBN|0-88022-856-3}} pages 73-75, page 94</ref> Besides the {{val|416&nbsp;KB|ul=kB}} of usable RAM for S/370 applications, the XT/370 also supported up to {{val|4 |ul=MB}} of [[virtual memory]] using the hard drive as its paging device.<ref name="killen1984fall">{{cite news | url=https://archive.org/stream/byte-magazine-1984-09/1984_09_BYTE_09-09_Guide_to_the_IBM_PCs#page/n33/mode/2up | title=IBM Forecast / Market Dominance | work=BYTE | date=Fall 1984 | accessdate=18 March 2016 | author=Killen, Michael | pages=30–38}}</ref>

IBM claimed the XT/370 reached 0.1 [[InstructionsMillion instructions per second|MIPS]] (when the data fit in RAM). In 1984, the list price of an XT/370 in its typical configuration was approximately {{US$12,000|long=no|12000}} so compared favorably with IBM's own mainframes on a $/MIPS basis; for example, an [[IBM 4341]] delivered 1.2&nbsp; MIPS for {{US$500,000|long=no|500000}}. While it theoretically reduced demand on customers' mainframes by offloading load onto the smaller computer, as customers purchased more XT/370s they likely increased the overall load on the mainframes, increasing IBM's mainframe sales.{{r|killen1984fall}}

The XT/370 was an [[IBM Personal Computer XT]] (System Unit 5160) with three custom 8-bit cards. The processor card (370PC-P),<ref>{{cite web |url=https://priorart.ip.com/IPCOM/000059679# |archive-url=https://web.archive.org/web/20151211060121/http://priorart.ip.com/IPCOM/000059679 |url-status=dead |archive-date=2015-12-11 |title=Implementation of IBM System 370 Via Co-Microprocessors/The Co-Processor... - IPCOM000059679D - IP.com |publisher=Priorartdatabase.com |date= |accessdate=2020-07-23 }}</ref> contained two modified [[Motorola_68000_series|Motorola 68000]] chips (which could emulate most S/370 fixed-point instructions and non-floating-point instructions), and an [[Intel 8087|Intel 8087 coprocessor ]] modified to emulate the S/370 floating point instructions. The second card (370PC-M), which connected to the first with a unique card back connector contained 512 [[Kibibyte|KiB]] of memory. The third card (PC3277-EM), was a 3270 terminal emulator required to download system software from the host mainframe. The XT/370 computer booted into DOS, then ran the [[VM (operating system)|VM]]/PC Control Program. The card's memory space added additional system memory, so the first 256 KiB ([[motherboard]]) memory could be used to move data to the 512 KiB expansion card. The expansion memory was dual ported, and provided an additional 384 KiB to the XT Machine bringing the total RAM on the XT side to 640 KiB. The memory arbitrator could bank switch the second 128 KiB bank on the card to other banks, allowing the XT [[Intel 8088]] processor to address all the RAM on the 370PC-M card.<ref name=Mueller92>Scott Mueller ''Upgrading and Repairing PCs, Second Edition'', Que Books, 1992, {{ISBN|0-88022-856-3}} pages 73-75, page 94</ref> Besides the 416&nbsp;KB of usable RAM for S/370 applications, the XT/370 also supported up to 4 MB of [[virtual memory]] using the hard drive as its paging device.<ref name="killen1984fall">{{cite news | url=https://archive.org/stream/byte-magazine-1984-09/1984_09_BYTE_09-09_Guide_to_the_IBM_PCs#page/n33/mode/2up | title=IBM Forecast / Market Dominance | work=BYTE | date=Fall 1984 | accessdate=18 March 2016 | author=Killen, Michael | pages=30–38}}</ref>

IBM claimed the XT/370 reached 0.1 [[Instructions per second|MIPS]] (when the data fit in RAM). In 1984, the list price of an XT/370 in its typical configuration was approximately $12,000 so compared favorably with IBM's own mainframes on a $/MIPS basis; for example, an [[IBM 4341]] delivered 1.2&nbsp;MIPS for $500,000. While it theoretically reduced demand on customers' mainframes by offloading load onto the smaller computer, as customers purchased more XT/370s they likely increased the overall load on the mainframes, increasing IBM's mainframe sales.{{r|killen1984fall}}

Similarly to the mainframe version of [[VM/CMS]], the VM/PC also created the illusion of [[Logical disk|virtual disks]], but on the PC version these were maintained as PC DOS files, either on floppy or hard disk. For example, the CMS virtual disk belonging to user FRED at device address 101 was stored as the DOS file FRED.101. The CMS IMPORT and EXPORT commands allowed extraction of files from these virtual drives as well as [[ASCII]]/[[EBCDIC]] conversion.<ref>BYTE Guide to the IBM PC, fall 1984, pp. 44-46</ref>

The XT/370 came with an XT-style 83-key keyboard (10 function keys).<ref name="byte1984fall">{{cite news | url=https://archive.org/stream/byte-magazine-1984-09/1984_09_BYTE_09-09_Guide_to_the_IBM_PCs#page/n13/mode/2up | title=IBM Personal Computers At a Glance | work=BYTE | date=Fall 1984 | accessdate=18 March 2016 | pages=10–26}}</ref> Newer revisions of the XT/370 dropped the PC3277-EM in favor of the IBM 3278/79 boards. The XT/370 was among the XT systems that could use a second hard drive mounted in the 5161 expansion chassis.<ref name="pc-service-information-manual">{{cite book|title=Personal Computer Family Service Information Manual|date=January 1989|publisher=IBM|id=SA38-0037-00|url=http://bitsavers.org/pdf/ibm/pc/SA38-0037-00_Personal_Computer_Family_Service_Information_Manual_Jul89.pdf}}</ref>{{rp|6-176–17}}

''[[BYTE]]'' in 1984 called the XT/370 "a qualified success". The magazine praised IBM for "fitting all of the 370's features into the XT", and hoped for technical improvements that "might result in an even better computer".<ref name="sabine1984fall">{{cite news | url=https://archive.org/stream/byte-magazine-1984-09/1984_09_BYTE_09-09_Guide_to_the_IBM_PCs#page/n217/mode/2up/search/5160 | title=The IBM XT/370 Personal Computer | work=BYTE | date=Fall 1984 | accessdate=18 March 2016 | author=Sabine, Ernest | pages=210–217}}</ref>

The XT/370 was discontinued in April 1987.<ref name=givesup>{{cite journal | date=April 13, 1987 | url=https://techmonitor.ai/technology/ibm_gives_up_on_the_personal_xt_at370 | title=IBM Gives Up on the Personal XT/, AT/370 | journal=Computer Business Review | publisher=New Statesman Media Group | archiveurl=https://archive.today/20230920021426/https://techmonitor.ai/technology/ibm_gives_up_on_the_personal_xt_at370 | archivedate=September 20, 2023}}</ref>

===Personal Computer AT/370===

In 1984, IBM introduced the IBM Personal Computer AT/370<ref>{{cite web|url=https://www-03.ibm.com/ibm/history/documents/pdf/1970-1984.pdf |archive-url=https://web.archive.org/web/20050310235403/http://www-03.ibm.com/ibm/history/documents/pdf/1970-1984.pdf |url-status=dead |archive-date=March 10, 2005 |title=IBM Highlights, 1970-1984 |publisher=IBM}}</ref> with similar cards as for the XT/370 and updated software, supporting both larger hard disks and <!-- 16-bit Dubious, see talk --> DMA transfers from the 3277 card to the AT/370 Processor card. The system was almost 60% faster than the XT/370.<ref name=Mueller92/> The AT/370 used different, 16-bit interface co-processing cards than the XT, called PC/370-P2 and PC/370-M2. The latter card still had only 512&nbsp;KB for memory, out of which 480&nbsp;KB were usable for programs in S/370 mode, while 32&nbsp;KB were reserved for microcode storage. For the terminal emulation function, the AT/370 came with the same 3278/79 Emulation Adapter as the late-series XT/370. The AT/370 motherboard itself was equipped with 512&nbsp;KB of RAM.<ref name="pc-service-information-manual"/>{{rp|9-26 to 9-28}}

The AT/370 also ran VM/PC, but with PC DOS 3.0 instead of 2.10 that the XT version used.<ref>Virtual Machine/Personal Computer User's Guide, p. 1-3, IBM publication number 6137739, December 1984</ref> VM/PC version 2, launched in November 1985, improved performance by up to 50%; it allowed add-on memory (in addition to the disk) to be used as a [[page cache]] for VM.<ref name="Gallant">{{cite journal|author=John Gallant|title=IBM exploiting AT/370 ability|journal=Computerworld : The Newsweekly of Information Systems Management|url=https://books.google.com/books?id=ZUMIDEwANHgC&pg=PA25|date=25 November 1985|publisher=Computerworld|pages=25, 29|issn=0010-4841}}</ref>

A November 1985 ''[[Computerworld]]'' article noted that the machine was "slow selling".<ref name="Gallant"/> The AT/370 was discontinued alongside the XT/370 in April 1987.<ref name=givesup />

===IBM 7437 VM/SP Technical Workstation===

In April 1988, IBM introduced a System/370 [[workstation]] that had been shipping to some customers since August 1987.<ref>{{cite magazine | last=Cortino | first=Juli | title=IBM 'personal mainframe' goes public this summer | magazine=PC Week | volume=6 | issue=16 | date=1989-04-24}}</ref> Officially called the IBM 7437 VM/SP Technical Workstation (and later also known as the Personal System/370), it was a freestanding tower that connected to a [[Micro Channel architecture|MCA]] card installed in a [[IBM Personal System/2|PS/2]] [[IBM PS/2 Model 60|Model 60]], 70, or 80. The 7437 tower contained the processor and a 16{{nbsp}}Mbytes main memory, and the PS/2 provided I/O and disk storage.<ref name=Cain>{{cite magazine | last=Cain | first=Matthew | title=IBM quietly sells a VM workstation: single-user system | magazine=MIS Week | volume=9 | issue=45 | date=1988-11-07 | page=8 |url=https://archive.org/details/sim_mis-week_1988-11-07_9_45/page/8}}</ref> The 7437 ran the IBM [[VM/SP]] operating system, and one IBM representative described the 7437 "like a [[IBM 9370|9370]] with a single terminal". It was intended for existing S/370 users and its November 1988 list price was $18,100 for a minimum 25-unit order.<ref>{{citation | last1=Fisher | first1=Sharon | last2=LaPlante | first2=Alice | title=IBM's VM/SP Device Cuts Mainframe Load | periodical=InfoWorld | volume=10 | issue=45 | page=113 | date=1988-11-07 | url=https://books.google.com/books?id=RzsEAAAAMBAJ&q=ibm%207437&pg=PT112}}</ref> One of its intended roles was to provide a single-user S/370-compatible computer that could run [[computer-aided design]] and [[Computer-aided engineering|engineering]] applications that originated on IBM mainframes such as [[CADAM]] and [[CATIA]]. Graphics support was provided by an IBM 5080 graphics system, a floor-standing tower. The 5080 was connected to the 7437 through the PS/2 via a cable and MCA adapter.<ref>{{cite magazine | last=Smalley | first=Eric | title=Quiet IBM Entry Lets Users Run VM on Desk Top | magazine=Digital Review | volume=5 | issue=22 | date=1989-11-21 | page=19}}</ref>

===Personal/370===

Line 41 ⟶ 44:

==System/390==

In 1995 IBM introduced a card, the "Enhanced S/390 MicroProcessor Complex", which supported [[IBM ESA/390]] architecture on a PC-based system.<ref>{{cite news|title=Pipeline - Announced|volume = 17|url=https://books.google.com/books?id=0joEAAAAMBAJ&pg=PA25|accessdate=Feb 14, 2018|work=Infoworld|issue=30|date=August 21, 1995}}</ref> IBM's PC-related products evolved to support that as well, employing the card (IBM part number 8640-PB0) in the "IBM PC Server 330 in 1998<ref>{{cite web|last1=IBM Corporation|title=IBM PC Server System/390 Hints and Tips|url=ftphttps://ftppublic.softwaredhe.ibm.com/hardware/p390/doc/p390/faqp390.htm|website=ibm.com|accessdateaccess-date=Feb 14, 2018}}</ref><ref>{{cite book|last1=IBM Corporation|title=IBM PC Server System/390 Quick Product Guide|date=1997|url=http://ps-2.kev009.com/p390/$P390manuals/P390_qrefp390.pdf|accessdateaccess-date=Feb 14, 2018}}</ref> and the IBM PC Server 500 models.<ref>{{cite web|last1=IBM Corporation|title=IBM PC Server 500 System/390 Delivers Two Computing Environments in One Cost-Effective Solution|url=http://www-01.ibm.com/common/ssi/rep_ca/7/897/ENUS195-147/index.html|website=ibm.com|date=23 May 1995 |accessdate=Feb 14, 2018}}</ref>

===S/390 Processor Card===

Line 52 ⟶ 55:

===R/390===

R/390 was the designation used for the expansion card used in an IBM RS/6000 server. The original R/390 featured a 67 or 77&nbsp;MHz [[POWER2]] processor and 32 to 512 MB of RAM, depending on the configuration. The [[Micro Channel architecture|MCA]] P/390 expansion card can be installed in any [[Micro Channel architecture|MCA]] RS/6000 system, while the [[Peripheral Component Interconnect|PCI]] P/390 card can be installed in a number of early [[Peripheral Component Interconnect|PCI]] RS/6000s; all such configurations are referred to as an R/390. R/390 servers need to run AIX version 4 as the host operating system.

[[File:IBM P390 (1).jpg|thumb|IBM PC Server 500. This server can contain a P/390 board.]]

===P/390===

P/390 was the designation used for the expansion card used in an [[IBM PC Server]] and was less expensive than the R/390. The original P/390 server was housed in an IBM PC Server 500 and featured a 90&nbsp;MHz [[Intel]] [[IntelPentium P5(original)|Pentium]] processor for running OS/2. The model was revised in mid-1996 and rebranded as the PC Server 520, which featured a 133&nbsp;MHz Intel Pentium processor. Both models came standard with 32&nbsp;MB of [[Random access memory|RAM]] and were expandable to 256&nbsp;MB. The PC Server 500 featured eight MCA expansion slots while the PC Server 520 added two [[Peripheral Component Interconnect|PCI]] expansion slots and removed two MCA slots.

===S/390 Integrated Server===

[[File:IBM S390s390 Integratedintegrated Serverserver (298844712261).jpg|thumb|TwoIBM S/390 ISIntegrated (on front)Server]]

The S/390 Integrated Server (aka S/390 IS) is a mainframe housed in a comparablycomparatively small case (HxWxD are 82 x 52 x 111&nbsp;cm). It became available from November 1998. It is intended for customers who do not require the I/O bandwidth and performance of the [[Multiprise 3000|S/390 Multiprise 3000]] (which has the same size). Only 256 MB of ECC Memory and a single CMOS main processor (performance about 8&nbsp;MIPS) are used; the S/390 CPU used in the Integrated Server is in fact the P/390 E-card. A [[Pentium II]] is used as IOSP (I/O Service Processor). It supports four [[ESCON]] and to four parallel channels. Standard PCI and ISA slots are present. A maximum of 255 GB internal harddisks are supported (16x 18GB HDs, with 2x HDs for redundancy). The supported OSs are OS/390, MVS/ESA, VM/ESA and VSE/ESA.

===Fujitsu PC-based mainframessystems===

Fujitsu offers two PC-compatiblebased systems that make up the lower end of Fujitsu's S/390-based [[BS2000]] mainframe product line.<ref>[https://globalsp.ts.fujitsu.com/dmsp/docs/wp_s175_s210_business-server.pdf]{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The SQ100 is the slower configuration, using dual-core 2.93{{nbsp}}GHz [[Xeon#Tigerton|Intel Xeon E7220]] processors, and is capable of up to 200RPF of performance.<ref>[https://globalsp.ts.fujitsu.com/dmsp/docs/ds_sq100-businessserver.pdf]{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The SQ200 was introduced more recently, uses six-core 2.66{{nbsp}}GHz [[Xeon#6500/7500-series "Beckton"|Xeon X7542]] processors, and has performance of up to 700RPF.<ref>[https://globalsp.ts.fujitsu.com/dmsp/docs/ds-sq200-businessserver-em-en.pdf]{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> All [[Intel 64]]-based BS2000 mainframes can run Linux or Windows in separate partitions. Fujitsu also continues to make custom S/390-native processors and mainframe hardware for the high end of its BS2000 line.<ref>{{cite web|url=http://ts.fujitsu.com/products/bs2000/s_series/s210.html |title=Business Server S210 - Fujitsu Technology Solutions |publisher=Ts.fujitsu.com |date= |accessdate=2012-06-07}}</ref>

== z/Architecture and today==

{{Multiple issues|section=yes|

{{update|section|date=February 2014}}

{{no footnotes|section|date=February 2014}}

{{undue weight|date=February 2014}}

}}

Line 73 ⟶ 76:

* '''FLEX-ES''' by Fundamental Software emulates both System/390 (ESA/390) and [[z/Architecture]]. Claimed to be one of the most popular PC-based IBM-compatible mainframe products (as of 2006). While FLEX-ES is capable of running on most PC hardware, the licensing agreement requires that FLEX-ES must run on the machine with which it was sold; in the past, this included Compaq Proliant and HP servers, but today this is nearly always an approved IBM [[IBM System x|x]]Series server or a [[ThinkPad]] laptop.

* '''[[Hercules (emulator)|Hercules]]''', an open source emulator for the System/370, System/390, and z/Architecture instruction sets. It does however require a complete operating system in order to execute application programs. While IBM does not license its current operating systems to run on Hercules, earlier System/370 operating systems are in the [[public ___domain]]{{Citation needed|date=February 2021}} and can be legally run on Hercules.

* '''[[zPDT]]''' (System/z Personal Development Tool), an IBM offering allowing IBM PartnerWorld Independent Software Developers (ISVs) to legally run [[z/OS]] 1.6 (or higher), [[IBM DB2|DB2]] V8 (or higher), [[z/VM]], [[z/TPF]], or [[z/VSE]] 4.1 (or higher) on PC-based machines that can be acquired based on a Linux emulation.

*'''IBM ZD&T''' (Z Development and Test Environment), an IBM offering ''provides an x86-based environment that emulates Z hardware and runs'' genuine ''z/OS software, offering unmatched application portability and compatibility. IBM Z Development and Test Environment can be used for education, demonstration, and development and test of applications that include mainframe components.''

* The [http://z390.org/ z390 ]Z390 and [http://zcobol.org/ zcobol]zCOBOL is a portable macro assembler and COBOL compiler, linker, and emulator toolkit providing a way to develop, test, and deploy mainframe compatible assembler and COBOL programs using any computer that supports J2SE 1.6.0+ runtime.

==Timeline==

{{Timeline of the IBM Personal Computer}}

==See also==

*[[List of IBM Personal Computer models]]

*[[List of IBM products]]

Line 92 ⟶ 99:

* [http://john.ccac.rwth-aachen.de:8000/alf/pcs500/ Detail pictures of a PC Server 500, on the private website of Alfred Arnold]

* [http://www.corestore.org/is.htm Detail pictures of a S/390 IS (incl. screenshot of console), on the private website of Michael J. Ross]

* [httphttps://wwwardent-tool.tavi.co.ukcom/ps2pages/ohlandP390/ P/390 Information] at '9595 Ardent Tool of Capitalism'

* [httphttps://wwwardent-tool.tavi.co.uk/ps2pagescom/ohlandP390/faq390.txt IBM PC Server System/390 FAQ] at '9595 Ardent Tool of Capitalism'

* [http://www.redbooks.ibm.com/redbooks/pdfs/sg247721.pdf zPDT: Introduction and Reference. (IBM Redbook)]

* [https://web.archive.org/web/20121007085342/http://www-01.ibm.com/support/docview.wss?uid=isg202fb2738dbf2f985852575cc00504942&aid=1 zPDT: User's guide (IBM Manual)]

* [https://web.archive.org/web/20110822215320/http://www.p390.com/updt.htm zPDT worldwide distributor]

* [https://web.archive.org/web/20120425154040/http://www.p390.com/redd.htm zPDT for Rational Developer for System z Unit Test]

* [http://www.cpushack.com/2013/03/22/cpu-of-the-day-ibm-micro-370/ Micro/370 - the chips used in the XT/370]

* {{Cite journal | doi = 10.1147/sj.233.0245| title = System/370 capability in a desktop computer| journal = IBM Systems Journal| volume = 23| issue = 3| pages = 245| year = 1984| last1 = Kozuh | first1 = F. T.| last2 = Livingston | first2 = D. L.| last3 = Spillman | first3 = T. C.}}

* [https://web.archive.org/web/20150621044331/http://nix.nasa.gov/search.jsp?R=19890005611&qs=N%3D4294554104 A performance evaluation of the IBM 370/XT personal computer], NASA{{Dead link|date=February 2021}}

* {{cite journal|last1=Webb|first1=Charles F.|title=S/390 microprocessor design|journal=IBM Journal of Research and Development|date=November 2000|volume=44|issue=6|pages=899–907|doi=10.1147/rd.446.0899|citeseerx=10.1.1.93.3220}}

{{div col end}}

{{IBM personal computers}}

[[Category:IBM System/360 mainframe line]]

[[Category:IBM PC compatibles]]

[[Category:X86 IBM personal computers|PC-based IBM-compatible mainframes]]

[[Category:IBM workstations]]

[[Category:IBM System/360 mainframe line]]