Editing IBM System/360 (section)

===Successors and variants===
System/360 (excepting the Models 20, 44<ref group=NB>There was no S/370 replacement for 44PS.</ref> and 67<ref group=NB>IBM did provide upgrades to [[CP-67/CMS]] and [[TSS/360]] that ran on S/370, but without 32-bit addressing.</ref>) was replaced with the compatible [[System/370]] range in 1970 and Model 20 users were targeted to move to the [[IBM System/3]]. (The idea of a major breakthrough with [[FS technology]] was dropped in the mid-1970s for cost-effectiveness and continuity reasons.) Later compatible IBM systems include the [[IBM 4300|4300 family]], the [[IBM 308X|308x family]], the [[IBM 3090|3090]], the [[IBM ES/9000 family|ES/9000]] and [[IBM 9672|9672]] families ([[System/390]] family), and the [[IBM Z]] series.

Computers that were mostly identical or compatible in terms of the machine code or architecture of the System/360 included [[Amdahl Corporation|Amdahl]]'s 470 family (and its successors), [[Hitachi]] mainframes, the [[UNIVAC 9000 series]],<ref name="sperry-rand-third-generation">{{cite journal | last1 = Gray | first1 = George T. | last2 = Smith | first2 = Ronald Q. | year = 2001 | title = Sperry Rand's Third-Generation Computers 1964-1980 | journal = [[IEEE Annals of the History of Computing]] | volume = 23 | issue = 1 | pages = 3–16 | publisher = [[IEEE Computer Society]] | doi = 10.1109/85.910845}}</ref> Fujitsu as the Facom, the [[RCA]] [[Spectra 70]] series,<ref group=NB>The RCA Spectra 70 had radically different architecture for interrupts and I/O. There were compatibility packages to allow operating systems for System/360 to run on a Spectra/70 and vice versa.</ref> and the [[English Electric System 4]].<ref group=NB>Intended for real-time processing, the English Electric System 4 employed four processor states, each with its own set of general-purpose registers. Instructions available in the user state were identical to the System/360. The other states were entered according to the class or severity of interrupt. The fourth (the highest) state was entered when power failure was imminent, and enabled the processor to shut itself down in an orderly fashion.</ref> The System 4 machines were built under license to RCA. RCA sold the Spectra series to what was then [[UNIVAC]], where they became the UNIVAC Series 70. UNIVAC also developed the [[UNIVAC Series 90]] as successors to the 9000 series and Series 70.<ref name="sperry-rand-third-generation"/> The [[Soviet Union]] produced a System/360 clone named the [[ES EVM]].<ref>{{cite web |url=http://www.redplenty.com/Logic.html |title=Account of Soviet cloning of the IBM-360, from ''Pioneers of Soviet Computing'' by Boris Malinovsky |access-date=2012-09-30 |archive-url=https://web.archive.org/web/20120829134126/http://www.redplenty.com/Logic.html |archive-date=2012-08-29 |url-status=dead}}</ref>

The [[IBM 5100]] portable computer, introduced in 1975, offered an option to execute the System/360's [[APL programming language|APL.SV programming language]] through a hardware emulator. IBM used this approach to avoid the costs and delay of creating a 5100-specific version of APL.

Special [[radiation hardened|radiation-hardened]] and otherwise somewhat modified System/360s, in the form of the [[System/4 Pi]] [[avionics]] computer, are used in several fighter and bomber jet aircraft. In the complete 32-bit AP-101 version, 4 Pi machines were used as the replicated computing nodes of the [[fault-tolerance|fault-tolerant]] [[Space Shuttle program|Space Shuttle]] computer system (in five nodes). The U.S. [[Federal Aviation Administration]] operated the [[IBM 9020]], a special cluster of modified System/360s for air traffic control, from 1970 until the 1990s. (Some 9020 software is apparently still used via [[emulator|emulation]] on newer hardware.{{citation needed|date=October 2017}})