Editing IBM System/370 (section)

==Series and models==

===Models sorted by date introduced (table)===
The following table summarizes the major S/370 series and models. The second column lists the principal architecture associated with each series. Many models implemented more than one architecture; thus, 308x processors initially shipped as S/370 architecture, but later offered XA; and many processors, such as the 4381, had microcode that allowed customer selection between S/370 or XA (later, ESA) operation.

Note also the confusing term "System/370-compatible", which appeared in IBM source documents to describe certain products. Outside IBM, this term would more often describe systems from [[Amdahl Corporation]], [[Hitachi]], and others, that could run the same S/370 software. This choice of terminology by IBM may have been a deliberate attempt to ignore the existence of those [[plug compatible manufacturer]]s (PCMs), because they competed aggressively against IBM hardware dominance.

{| class="wikitable"
! First year<br />of series !! Architecture !! Market<br />level !! Series !! Models 
|-
| 1970 || System/370 (no DAT) || high-end || rowspan="5" | System/370-xxx || -155, -165, -195
|-
| 1970 || System/370 (DAT) || mid-range || -145<ref name="model145">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3145.html|title=System/370 Model 145|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230729090334/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3145.html|archive-date=2023-07-29|url-status=dead}}</ref> and -135
|-
| rowspan="3" | 1972 || rowspan="3" | System/370 || high-end || -158 and -168
|-
| entry || -115 and -125
|-
| mid-range || -138 and -148
|-
| 1977 || rowspan="3" | System/370-compatible<ref>{{cite web|url=http://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_basinfo.html|title=IBM timeline of S/370 series| website=[[IBM]] |date=23 January 2003}} with surprising term 'System/370-compatible' for the 3xxx and 4xxx series</ref> || high-end || [[IBM 303X|303x]] || 3031, 3032, 3033
|-
| 1979 || entry/mid || [[IBM 4300|43xx]] || 4331, 4341, 4361
|-
| 1980 || rowspan="2" | high-end || rowspan="2" | [[IBM 308X|308x]] || rowspan="2" | 3081, 3083, 3084
|-
| 1981 || rowspan="3" | System/370-XA
|-
| 1983 || mid-range || [[IBM 4300|4381]] || 4381
|-
| 1986 || high-end || [[IBM 3090|3090]] || -120 to -600
|-
| 1986 || System/370-compatible<ref>{{cite web|url=https://www.ibm.com/docs/en/announcements/archive/ENUS186-178|title=IBM 9370 Information System Overview|type=Announcement letter|publisher=[[IBM]] |date=7 October 1986}} to explain why the 9370 is categorized as a System/370 compatible system
</ref> || entry || [[IBM 9370|937x]] || 9370, ...
|-
| 1988 || rowspan="2" | ESA/370 || high-end || ES/3090 || ES/3090
|-
| 1988 || mid-range || ES/4381 || -90, -91, -92 
|}

===Models grouped by Model number (detailed)===
[[List of IBM products#Later solid-state computers & systems|IBM]] used the name System/370 to announce the following eleven (three-digit) offerings:

====System/370 Model 115====
The '''IBM System/370 Model 115''' was announced March 13, 1973<ref name="IBM370.115">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3115.html|title=System/370 Model 115|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719144824/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3115.html|archive-date=2023-07-19|url-status=dead}}</ref> as "an ideal System/370 entry system for users of [[IBM System/3|IBM's System/3]], [[IBM 1130|1130 computing system]] and [[IBM System/360 Model 20|System/360 Models 20]], [[IBM System/360 Model 22|22]] and [[IBM System/360 Model 25|25]]."

It was delivered with "a minimum of two (of IBM's newly announced) directly attached [[IBM 3340]] disk drives."<ref name="IBM370.115"/> Up to four 3340s could be attached.

The CPU could be configured with 65,536 (64K) or 98,304 (96K) bytes of main memory. An optional 360/20 emulator was available.

The 115 was withdrawn on March 9, 1981.

====System/370 Model 125====
The '''IBM System/370 Model 125''' was announced Oct 4, 1972.<ref name="IBM370.125">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3125.html|title=System/370 Model 125|website=IBM Archives| date=23 January 2003 |publisher=IBM|archive-url=https://web.archive.org/web/20230719145726/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3125.html|archive-date=2023-07-19|url-status=dead}}</ref>

Two, three or four directly attached [[IBM 3333]] disk storage units provided "up to 400 million bytes online."

Main memory was either 98,304 (96K) or 131,072 (128K) bytes.

The 125 was withdrawn on March 9, 1981.

====System/370 Model 135====
The '''IBM System/370 Model 135''' was announced Mar 8, 1971.<ref name="IBM370.135">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3135.html|title=System/370 Model 135|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719221316/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3135.html|archive-date=2023-07-19|url-status=dead}}</ref> Options for the 370/135 included a choice of four main memory sizes; [[IBM 1400 series]] (1401, 1440 and 1460) emulation was also offered.

A "reading device located in the Model 135 console" allowed updates and adding features to the Model 135's microcode.

The 135 was withdrawn on October 16, 1979.

====System/370 Model 138====
The '''IBM System/370 Model 138''' which was announced Jun 30, 1976 was offered with either 524,288 (512K) or 1,048,576 (1 MB) of memory. The latter was "double the maximum capacity of the Model 135," which "can be upgraded to the new computer's internal performance levels at customer locations."<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3138.html|title=System/370 Model 138|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719144824/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3138.html|archive-date=2023-07-19|url-status=dead}}</ref>

The 138 was withdrawn on November 1, 1983.

====System/370 Model 145====
{{main article|IBM System/370 Model 145}}

The '''IBM System/370 Model 145''' was announced Sep 23, 1970, three months after the 155 and 165 models.<ref name="model145"/> It first shipped in June 1971.<ref name="Pugh91" />{{rp|643}}

The first System/370 to use monolithic main memory, the Model 145 was offered in six memory sizes. A portion of the main memory, the "Reloadable Control Storage" (RCS) was loaded from a prewritten disk cartridge containing [[microcode]] to implement, for example, all needed instructions, I/O channels, and optional instructions to enable the system to emulate earlier IBM machines.<ref name="model145" />

The 145 was withdrawn on October 16, 1979.

====System/370 Model 148====
The '''IBM System/370 Model 148''' had the same announcement and withdrawal dates as the Model 138.<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3148.html|title=System/370 Model 148|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719145815/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3148.html|archive-date=2023-07-19|url-status=dead}}</ref>

As with the option to field-upgrade a 135, a 370/145 could be field-upgraded "at customer locations" to 148-level performance. The upgraded 135 and 145 systems were "designated the Models 135-3 and 145-3."

====System/370 Model 155====
{{main article|IBM System/370 Model 155}}

The '''IBM System/370 Model 155''' and the Model 165 were announced Jun 30, 1970, the first of the 370s introduced.<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3155.html|title=System/370 Model 155|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230516082850/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3155.html|archive-date=2023-05-16|url-status=dead}}</ref> Neither had a DAT box; they were limited to running the same non-virtual-memory operating systems available for the [[IBM System/360|System/360]]. The 155 first shipped in January 1971.<ref name="Pugh91" />{{rp|643}}

The ''OS/DOS''<ref>{{cite book
 | title = IBM System/360 Operating System: DOS Emulator Planning Guide
 | id = GC24-5076
 | publisher = IBM
 }}
</ref> (DOS/360 programs under OS/360), ''1401/1440/1460 and 1410/7010''<ref>{{cite book
 | publisher = IBM
 | title = Emulating the IBM 1401, 1440 and 1460 on the IBM System/370 Models 145 and 155 using OS/360 Program Number 360C-EU-735
 | id = GC27-6945-1
 | edition = Second
 | date = February 1971
 | mode = cs2
 }}
</ref><ref>{{cite book
 | publisher = IBM
 | title = Emulating the IBM 1410 and 7010 on the IBM System/370 Models 145 and 155 using OS/360 Program Number 360C-EU-736
 | id = GC27-6946-1
 | edition = Second
 | date = June 1971
 | mode = cs2
 }}
</ref> and ''7070/7074'' <ref>{{cite book
 | publisher = IBM
 | title = Emulating the IBM 7074 on the IBM System/370 Models 155 and 165 using OS/360 Program Number 360C-EU-739
 | id = GC27-6948-1
 | edition = Second
 | date = February 1971
 }}
</ref> compatibility features  were included, and the supporting integrated emulator programs could operate concurrently with standard System/370 workloads.

In August 1972 IBM announced, as a field upgrade only, the '''IBM System/370 Model 155 II''', which added a DAT box.

Both the 155 and the 165 were withdrawn on December 23, 1977.

====System/370 Model 158====
The '''IBM System/370 Model 158''' and the 370/168 were announced Aug 2, 1972.<ref name="IBM370.158">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3158.html|title=System/370 Model 158|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20210301143132/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3158.html|archive-date=2021-03-01|url-status=dead}}</ref>

It included dynamic address translation (DAT) hardware, a prerequisite for the new [[virtual memory]] operating systems (DOS/VS, OS/VS1, OS/VS2).

A tightly coupled multiprocessor (MP) model was available, as was the ability to loosely couple this system to another 360 or 370 via an optional channel-to-channel adapter.

The 158 and 168 were withdrawn on September 15, 1980.

====System/370 Model 165====
{{main article|IBM System/370 Model 165}}

The '''IBM System/370 Model 165''' was described by IBM as "more powerful"<ref name="Model-165-IBM-Archives" /> compared to the "medium-scale" 370/155. It first shipped in April 1971.<ref name="Pugh91" />{{rp|643}}

Compatibility features included [[Emulator|emulation]] for [[IBM 700/7000 series|7070/7074, 7080, and 709/7090/7094/7094 II]].

Some have described the [[IBM System/360 Model 85|360/85]]'s use of [[microcode]]d vs [[Hardwired control unit|hardwired]] as a bridge to the 370/165.<ref>{{cite newsgroup|url=https://groups.google.com/d/topic/alt.folklore.computers/OHWBCMBqwKY|title=IBM 360/85 vs. 370/165|author=Jon Elson|newsgroup=alt.folklore.computers|date=December 5, 2014}}</ref>

In August 1972 IBM announced, as a field upgrade only, the '''IBM System/370 Model 165 II''' which added a DAT box.

The 165 was withdrawn on December 23, 1977.

====System/370 Model 168====
{{main|IBM System/370 Model 168}}

The '''IBM System/370 Model 168''' included "up to eight megabytes"<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3168.html|title=System/370 Model 168|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20231205223819/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3168.html|archive-date=2023-12-05|url-status=dead}}</ref> of main memory, double the maximum of 4 megabytes on the 
370/158.<ref name="IBM370.158"/>

It included dynamic address translation (DAT) hardware, a pre-requisite for the new [[virtual memory]] operating systems.

Although the 168 served as IBM's "flagship" system,<ref name=FLAG3>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/3033/3033_intro.html|title=IBM's 3033 "The Big One": IBM's 3033|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230928083308/https://www.ibm.com/ibm/history/exhibits/3033/3033_intro.html|archive-date=2023-09-28|url-status=dead}}</ref> a 1975 newsbrief said that IBM boosted the power of the 370/168 again "in the wake of the Amdahl challenge... only 10 months after it introduced the improved 168-3 processor."<ref>{{cite news|newspaper=[[Computer Weekly]]|year=1975|issue=486|page=1|url=http://www.tnmoc.org/news/notes-museum/winter-19756-pages-computer-weekly|title=IBM boosts power of 370/168 again|archive-url=https://web.archive.org/web/20151208061017/http://www.tnmoc.org/news/notes-museum/winter-19756-pages-computer-weekly|archive-date=December 8, 2015}}</ref>

The 370/168 was not withdrawn until September 1980.

====System/370 Model 195====
[[File:CHM Artifacts (3300701247).jpg|thumb|Model 195 control panel]]
The '''IBM System/370 Model 195''' was announced Jun 30, 1970 and, at that time, it was "IBM's most powerful computing system."<ref name="ibm-archives-3195">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3195.html|title=System/370 Model 195|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230729090333/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3195.html|archive-date=2023-07-29|url-status=dead}}</ref>

Its introduction came about 14 months after the announcement of its direct predecessor, the [[IBM System/360 Model 195|360/195]]. Both 195 machines were withdrawn Feb. 9, 1977.<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2195.html|title=System/360 Model 195|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230729090329/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2195.html|archive-date=2023-07-29|url-status=dead}}</ref><ref name="ibm-archives-3195"/>

====System/370-compatible====
Beginning in 1977, IBM began to introduce new systems, using the description "A compatible member of the System/370 family."<ref name="IBM.3031">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3031.html|title=3031 Processor Complex|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719144802/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3031.html|archive-date=2023-07-19|url-status=dead}}</ref><ref>{{cite web|url=http://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_basinfo.html|title=Mainframes - Basic information sources|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230922112055/http://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_basinfo.html|archive-date=2023-09-22|url-status=dead}}</ref>

=====IBM 303X=====
{{main article|IBM 303X}}

The first of the initial high end machines, IBM's '''3033''', was announced March 25, 1977<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/3033/3033_PR01.html|title=3033 Press announcement|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719145845/https://www.ibm.com/ibm/history/exhibits/3033/3033_PR01.html|archive-date=2023-07-19|url-status=dead}}</ref> and was delivered the following March, at which time a multiprocessor version of the 3033 was announced.<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/3033/3033_PR02.html|title=3033 Multiprocessor - Press announcement|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719223056/https://www.ibm.com/ibm/history/exhibits/3033/3033_PR02.html|archive-date=2023-07-19|url-status=dead}}</ref> IBM described it as "The Big One."<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/3033/3033_intro.html|title=IBM's 3033 "The Big One": IBM's 3033|website=IBM Archives|date=23 January 2003|publisher=IBM|quote=''THINK'' magazine later simply dubbed it {{ndash}} "The Big One."|archive-url=https://web.archive.org/web/20230928083308/https://www.ibm.com/ibm/history/exhibits/3033/3033_intro.html|archive-date=2023-09-28|url-status=dead}}</ref>

IBM noted about the 3033, looking back, that "When it was rolled out on March 25, 1977, the 3033 eclipsed the internal operating speed of the company's previous flagship the System/370 Model 168-3 ..."<ref name=FLAG3/>

The IBM '''3031''' and IBM '''3032''' were announced Oct. 7, 1977 and withdrawn Feb. 8, 1985.<ref name="IBM.3031"/><ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3032.html|title=3032 Processor Complex|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719144906/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3032.html|archive-date=2023-07-19|url-status=dead}}</ref>

=====IBM 308X=====
{{main article|IBM 308X}}

Three systems comprised the next series of high end machines, IBM's 308X systems:
* The '''3081'''<ref name="IBM.3081">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3081.html|title=3081 Processor Complex|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719144956/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3081.html|archive-date=2023-07-19|url-status=dead}}</ref> (announced Nov 12, 1980) had 2 [[Central processing unit|CPU]]s
* The '''3083'''<ref name="IBM.3083">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3083.html|title=3083 Processor Complex|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719144956/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3083.html|archive-date=2023-07-19|url-status=dead}}</ref> (announced Mar 31, 1982) had 1 CPU
* The '''3084'''<ref name="IBM.3084">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3084.html|title=3084 Processor Complex|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20231210232532/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3084.html|archive-date=2023-12-10|url-status=dead}}</ref> (announced Sep 3, 1982) had 4 CPUs

Despite the numbering, the least powerful was the 3083, which could be field-upgraded to a 3081;<ref name="IBM.3083"/> the 3084 was the top of the line.<ref name="IBM.3084"/>

These models introduced IBM's [[31-bit|Extended Architecture]]'s 31-bit address capability{{sfn|S370-XA-1st}} and a set of [[Backward compatibility|backward compatible]] MVS/Extended Architecture (MVS/XA) software replacing previous products and part of OS/VS2 R3.8:
{| class="wikitable"
|-
! Number
! style="align:left;" | Name
|-
| 565–279
| Basic Telecommunications Access Method/System Product (BTAM/SP)
|-
| 5668–978
| Graphics Access Method/System Product (GAM/SP)
|-
| 5740-XC6
| MVS/System Product - JES2 Version 2
|-
| 5685–291
| MVS/System Product - JES3 Version 2 
|-
| 5665–293
| TSO Extensions (TSO/E) for MVS/XA<ref>{{cite web
 | title = TSO Extensions (TSO/E), which enhances and extends the capability of TSO, is announced
 | id = ZP81-0796
 | date = November 2, 1981
 | url = https://www.ibm.com/docs/en/announcements/archive/ENUSZP81-0796
 | type = Announcement letter
 | publisher = IBM
 }}
</ref>
|-
| 5665–284
| MVS/Extended Architecture Data Facility Product (DFP) Version 1<ref name="dfp-1-2-general-information">{{cite book
 | title = MVS/Extended Architecture Data Facility Product: General Information
 | date = January 1984
 | edition = Third
 | url = http://bitsavers.org/pdf/ibm/370/MVS_XA/DFP/GC26-4007-2_MVS_XA_DFP_Release_1.2_General_Information_Jan1984.pdf
 | publisher = IBM
 | access-date = 2024-09-19
 }}</ref>
|}

All three 308x systems were withdrawn on August 4, 1987.

=====IBM 3090=====
{{main article|IBM 3090}}

The next series of high-end machines, the '''IBM 3090''', began with models{{efn|IBM used a lower case "m"}} 200 and 400.<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3090.html|title=3090 Processor Complex|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20231204192300/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP3090.html|archive-date=2023-12-04|url-status=dead}}</ref> They were announced Feb. 12, 1985, and were configured with two or four [[Central processing unit|CPU]]s respectively. IBM subsequently announced models 120, 150, 180, 300, 500 and 600 with lower, intermediate and higher capacities; the first digit of the model number gives the number of central processors.

Starting with the E<ref>{{cite web|url=https://www.ibm.com/docs/en/announcements/archive/ENUS187-110|title=IBM 3090 Processor Unit Model 120E, IBM 3092 Processor Controller Model 3|type=Announcement letter|publisher=IBM|date=May 19, 1987}}</ref> models, and continuing with the J and S models, IBM offered Enterprise Systems Architecture/370{{sfn|S370-ESA}} (ESA/370), [[Processor Resource/System Manager]] (PR/SM) and a set of backward compatible MVS/Enterprise System Architecture (MVS/ESA) software replacing previous products:

{| class="wikitable"
|-
! Number
! syle="text-align:left" | Name
|-
| 5685–279
| BTAM/SP
|-
| 5668–978
| GAM/SP 2.0
|-
| 5685–001
| MVS/System Product-JES2 Version 3<ref name=SP3>{{cite book
 | title = 5685-001 MVS/System Product-JES2 Version 3 Release 1.0
 | series = IBM Sales Manual
 | date = 8 August 2001
 | url = https://www.ibm.com/common/ssi/cgi-bin/ssialias?infotype=dd&subtype=sm&htmlfid=897/ENUS5685-001#Header_43
 | publisher = IBM
 | archive-url = https://web.archive.org/web/20220411014116/https://www.ibm.com/common/ssi/cgi-bin/ssialias?infotype=dd&subtype=sm&htmlfid=897/ENUS5685-001#Header_43
 | archive-date = 11 April 2022
 | url-status = dead
 }}
</ref>
|-
| 5685–002
| MVS/System Product-JES3 Version 3<ref name=SP3/>
|-
| 5665–293
| TSO Extensions (TSO/E) for MVS/XA
|-
| 5685–285
| TSO/E Version 1 Release 4
|-
| 5685–025
| TSO/E Version 2
|-
| 5665–284
| MVS/XA Data Facility Product (DFP) Version 1<ref name="dfp-1-2-general-information" />
|-
| 5665-XA2
| MVS/XA Data Facility Product (DFP) Version 2.3
|-
| 5665-XA3
| MVS/DFP Version 3.1
|}

IBM's offering of an optional vector facility (VF) extension for the 3090 came at a time when [[Vector processing]]/Array processing suggested names like [[Cray]] and [[Control Data Corporation]] (CDC).<ref>the hyperlink on the words "Vector processing" point to an article that has only 2 mentions of IBM, one of which begins "In 2000, IBM, Toshiba and Sony collaborated."</ref><ref>The "first to market" advantage can be summarized as "In 1972, computer designer Seymour Cray left CDC and formed a new company" as noted in Getting Up to Speed: The Future of Supercomputing, 2005, {{ISBN|0309165512}}, by National Research Council, Division on Engineering and Physical Sciences, Computer Science and Telecommunications Board</ref>

The 200 and 400 were withdrawn on May 5, 1989.

=====IBM 4300=====
{{main article|IBM 4300}}

The first pair of '''IBM 4300''' processors were Mid/Low end systems announced Jan 30, 1979<ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4331.html|title=4331 Processor|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20231209132724/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4331.html|archive-date=2023-12-09|url-status=dead}}</ref><ref>{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4341.html|title=4341 Processor|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719223403/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4341.html|archive-date=2023-07-19|url-status=dead}}</ref> as "compact (and).. compatible with System/370."

The 4331 was subsequently withdrawn on November 18, 1981, and the 4341 on February 11, 1986.

Other models were the 4321,<ref>{{Cite web|url=https://www.ibm.com/ibm/history/exhibits/dpd50/dpd50_chronology5.html|title=IBM Archives: DPD chronology - page 5| website=[[IBM]] |date=23 January 2003 |archive-url=https://web.archive.org/web/20201021214611/https://www.ibm.com/ibm/history/exhibits/dpd50/dpd50_chronology5.html |archive-date=2020-10-21}}</ref> 4361<ref name="IBM.4361">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4361.html|title=4361 Processor|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230914064000/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4361.html|archive-date=2023-09-14|url-status=dead}}</ref> and 4381.<ref name="IBM.4381">{{cite web|url=https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4381.html|title=4381 Processor|website=IBM Archives|date=23 January 2003|publisher=IBM|archive-url=https://web.archive.org/web/20230719145726/https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP4381.html|archive-date=2023-07-19|url-status=dead}}</ref>

The 4361 has "Programmable Power-Off -- enables the user to turn off the processor under program control";<ref name="IBM.4361"/> "Unit power off" is (also) part of the 4381 feature list.<ref name="IBM.4381"/>

IBM offered many Model Groups and models of the 4300 family,{{efn|One announcement alone featured mention of "Twelve models of the 4381" for just 3 "Model Groups" and also listed 6 other Model Groups}} ranging from the entry level 4331 to the 4381, described as "one of the most powerful and versatile intermediate system processors ever produced by IBM."{{efn|The same IBM web page notes the following date announced/withdrawn dates: Model Groups '''1 & 2''' (Sep 15, 1983 - Feb 11, 1986), Model Group '''3''' (Oct 25, 1984 - Feb 11, 1986), Model Groups '''11, 12, 13 & 14''' (announced Feb 11, 1986), Model Groups '''21, 22, 23 & 24''' (May 19, 1987 - Aug 19, 1992).}}

The 4381 Model Group 3 was dual-CPU.

=====IBM 9370=====
{{main article|IBM 9370}}

This low-end system, announced October 7, 1986,<ref>{{cite web
|url=http://www.ibm.com/common/ssi/cgi-bin/ssialias?subtype=ca&infotype=an&appname=iSource&supplier=897&letternum=ENUS186-178&open&cm_mmc=5733-_-n-_-vrm_newsletter-_-10207_134134&cmibm_em=dm:0:12046832
|title=IBM 9370 INFORMATION SYSTEM OVERVIEW
|date=October 7, 1986|publisher=IBM}}</ref> was "designed to satisfy the computing requirements of IBM customers who value System/370 affinity" and "small enough and quiet enough to operate in an office environment."

IBM also noted its sensitivity to "entry software prices, substantial reductions in support and training requirements, and modest power consumption and maintenance costs."

Furthermore, it stated its awareness of the needs of small-to-medium size businesses to be able to respond, as "computing requirements grow," adding that "the IBM 9370 system can be easily expanded by adding additional features and racks to accommodate..."

This came at a time when [[Digital Equipment Corporation]] (DEC) and its [[VAX]] systems were strong competitors in both hardware and software;<ref>{{cite web
|url=http://inspirehep.net/record/312767/files/ssc-n-691.pdf
|title=Report Of The SSC Computer Planning Committee
|at=chapter 5.4, "SUMMARY OF RELATIVE STRENGTH OF DEC/VMS AND IBM/VM" |date=January 1990}}</ref> the media of the day carried IBM's alleged "VAX Killer" phrase, albeit often skeptically.<ref>{{cite news |newspaper=[[The New York Times]]
  |url=https://www.nytimes.com/1988/01/03/business/the-moment-of-truth-for-big-blue.html
  |title=The Moment of Truth for Big Blue
  |quote=appears to be slaying precious few Vaxes
  |author=David E. Sanger  |date=January 3, 1988}}</ref>

===Clones===
In the 360 era, a number of manufacturers had already standardized upon the IBM/360 instruction set and, to a degree, 360 architecture. Notable computer makers included [[Univac]] with the [[UNIVAC 9000 series]], [[RCA]] with the [[RCA Spectra 70]] series, [[English Electric]] with the [[English Electric System 4]], and the Soviet [[ES EVM]]. These computers were not perfectly compatible, nor (except for the Russian efforts)<ref>{{cite magazine |magazine=[[Wired (magazine)|Wired]]  |date=November 1997
  |url=https://www.wired.com/1997/11/heartof
  |title=Heart of Darkness
  |author=David S. Bennahum
  |quote=from 1967 to 1972, it put in place a massive industrial complex to reverse-engineer, copy, and produce IBM mainframes and DEC minicomputers... Once a computer was reduced to its constituent bits on both a software and hardware level, industrial management designed a manufacturing process to replicate the machine... a clone of the IBM 360/40 in 1970, a Cold War coup. Later, he worked on duplicating the IBM 370}}</ref><ref>Re the 370 (followup to 360/40 clone): {{cite news |newspaper=[[The Washington Post]]
|url=https://www.washingtonpost.com/archive/politics/1985/09/24/soviet-radar-allegedly-stolen-from-us/3a754179-c337-4d60-8471-2e7b1d76f6bd/?noredirect=on
|title=Soviet Radar Allegedly Stolen From U.S.
|author=Michael Weisskopf  |date=September 24, 1985}}</ref> were they intended to be.

That changed in the 1970s with the introduction of the IBM/370 and [[Gene Amdahl]]'s launch of his own company. About the same time, Japanese giants began eyeing the lucrative mainframe market both at home and abroad. One Japanese consortium focused upon IBM and two others from the [[BUNCH]] ('''B'''urroughs/'''U'''nivac/'''N'''CR/'''C'''ontrol Data/'''H'''oneywell) group of IBM's competitors.<ref>{{cite news  |newspaper=[[The New York Times]]
  |url=https://www.nytimes.com/1984/02/05/business/bailing-out-of-the-mainframe-industry.html
  |title=Bailing Out Of The Mainframe Industry
  |quote=an acronym for Burroughs, ... and Honeywell
  |author=David E. Sanger |date=February 5, 1984}}</ref> The latter efforts were abandoned and eventually all Japanese efforts focused on the IBM mainframe lines.

Some of the era's clones included:
{{columns-list|colwidth=18em|
* [[Amdahl Corporation]] 470 series
* [[ES EVM]]
* [[Fujitsu]]
* [[Hitachi]]
* [[Magnuson Computer Systems]]
* [[Mitsubishi]]
* [[Siemens]]
* Two Pi Corporation<ref>{{cite journal
 |url=https://ieeexplore.ieee.org/document/1647006  |title=Microprocessor-based minicomputer runs IBM 370 software |date=June 1978
 |journal=Computer |volume=11 |issue=6 |pages=87–90 |publisher=IEEE |doi=10.1109/C-M.1978.218231 |access-date=July 1, 2021 |quote=The plug-compatible CPU is the conception of Dr. Jared A. Anderson and his associates at Two Pi Corp., ..|last1=Michalopoulos |first1=D. A. |url-access=subscription }}</ref>
* [[Univac]]
}}