Editing RSX-11 (section)

==History==
===Name and origins===
RSX-11 began as a port to the PDP-11 architecture of the earlier [[RSX-15]] operating system for the [[PDP-15]] minicomputer,<ref name="cutler-interview">{{cite interview |last=Cutler|first=Dave|subject-link=Dave Cutler|interviewer=Grant Saviers|title=Dave Cutler Oral History|url=https://www.youtube.com/watch?v=29RkHH-psrY |archive-url=https://ghostarchive.org/varchive/youtube/20211211/29RkHH-psrY| archive-date=2021-12-11 |url-status=live|publisher=Computer History Museum|date=2016-02-25|website=youtube.com|access-date=2021-02-26}}{{cbignore}}</ref> first released in 1971.<ref>RSX-15 release date taken  from:{{cite web
 |url=http://bitsavers.trailing-edge.com/pdf/dec/pdp15/DEC-15-GRQA-D_RSX15_1971.pdf
 |title= RSX-15 Real Time Executive reference manual
 |publisher=Digital Equipment Corporation
 |date=1971
 |access-date= 4 December 2017
 }}</ref>
The main architect for RSX-15 (later renamed XVM/RSX) was Dennis “Dan” Brevik.<ref>{{Cite web|url=http://www.miim.com/faq/general.shtml|title=General FAQ|website=www.miim.com|access-date=2019-12-10}}</ref><ref>{{cite web
 |url          = http://www.demillar.com/RSX/lacroute.pdf
 |title        = Reference letter for Dan Brevick
 |last         = Lacroute
 |first        = Bernard
 |date         = 3 May 1982
 |language     = en
 |archive-url  = https://web.archive.org/web/20050118011030/http://www.demillar.com/RSX/lacroute.pdf
 |archive-date = 18 January 2005
 |url-status   = dead
 |access-date  = 4 December 2017
}}</ref>

Commenting on the ''RSX'' acronym, Brevik says:<ref>{{cite web
| url=http://www.miim.com/faq/general.shtml
| title=RSX FAQ, General
| access-date=4 December 2017}}</ref>
{{Blockquote
|text="At first I called the new system DEX-15.  It was an acronym for 'Digital's Executive - for the PDP-15.'  The homonymic relation between DEC, DEX and deques (used as the primary linkage mechanism in the kernel) appealed to my sense of whimsy.  People readily adopted the acronym without question.

	But in a short time I was asked to submit the choice to the corporate legal department for a trademark search and registration.  They sent me a memo that DEX was already trademarked by some paper company and I would have to rename the product.  I pointed out to them that software and paper mills didn't seem to have a hell of a lot of connection, but they wouldn't budge.

	So I sat down with pencil and paper, and in a few moments came up with better than a dozen candidate acronyms and names.  My purpose was to come up with a good acronym and then find some appropriate words to justify it.  For example, X always appealed to me as part of an acronym because it is pronounced so forcefully, inferring (at least to me) some power and drama.  I used a lot of X's.  These potential acronyms were submitted back to the legal department.  At the time I had no favorite.
	
In a week or so they came back with a subset of my list that they could accept as trademarks.  It was left to me to make the final choice.
	
Bob Decker and I met in my office one afternoon to discuss the choice.  Bob was a marketeer who worked for me.  I chalked all the candidates on the blackboard and we started going through them one by one, pronouncing each out loud, savoring the sound, trying to get the feel of each one.  After ten minutes or so we had narrowed down the selection to three.
	
Bob sat back in silence as I kept looking at each acronym, seeing how it flowed off my tongue, what impression it gave me, and most importantly, the overall feeling about it.  After three or four minutes a strong feeling came over me about one of them.  It really felt right.  I looked at Bob and announced, "It's RSX".  I went to the board and erased all the rest until the only writing left was RSX.  It even looked right.
	
I have absolutely no memory about the other candidate acronyms.  They are lost forever, I suppose.  Well, maybe there's just a chance that the legal department kept copies of the correspondence - after all they are lawyers and they seem to hold on to everything (especially my money).
	
Oh, by the way, the acronym stood for 'Real-Time System Executive.'  Years later that was changed to 'Resource Sharing Executive,' which I think is even better.

...And that is how RSX got its name, on the 3rd floor of building 5 in the old mill."|sign=|source=}}

===RSX-11D and IAS=== 
The porting effort first produced small paper tape based real-time executives (RSX-11A, RSX-11C) which later gained limited support for disks (RSX-11B).<ref name="cutler-interview" /> RSX-11B then evolved into the fully fledged RSX-11D disk-based operating system, which first appeared on the [[PDP-11/40]] and [[PDP-11/45]] in early 1973.<ref name=DEChist75>{{cite book
|title=DIGITAL EQUIPMENT CORPORATION - Nineteen Fifty-Seven To The Present
|url=http://s3data.computerhistory.org/pdp-1/dec.digital_1957_to_the_present_(1978).1957-1978.102630349.pdf
|date=1975 |publisher=Digital Equipment Corporation}}</ref> The project leader for RSX-11D up to version 4 was [[Henry Krejci]].

While RSX-11D was being completed, Digital set out to adapt it for a small [[memory footprint]], giving birth to RSX-11M, first released in 1973. From 1971<ref name="NT_Introduction">{{cite web
   |url=http://tech-insider.org/windows/research/1992/11.html
   |title=Foreword to Inside Windows NT, by Helen Custer
   |author=David Cutler  |date=1993  |access-date=4 December 2017}}</ref> to 1976, the RSX-11M project was spearheaded by noted operating system designer [[Dave Cutler]], then at his first project.<ref name="NT_Introduction" /> Principles first tried in RSX-11M appear also in later designs led by Cutler, DEC's [[OpenVMS|VMS]] and [[DEC MICA|MICA]] and Microsoft's [[Windows NT]].<ref name="Russinovich">{{cite web
|url=http://www.itprotoday.com/management-mobility/windows-nt-and-vms-rest-story
|title=Windows NT and VMS: The Rest of the Story
|author=Mark Russinovich  |date=30 November 1998 |access-date=4 December 2017  |author-link=Mark Russinovich}}</ref><ref name="NT_lineage">While Windows NT system is in some areas a conceptual descendant of RSX-11M and VMS, its architecture descends directly from the [[DEC MICA|MICA]] operating system, which Cutler developed for the unreleased [[DEC PRISM|PRISM]] processor. See: {{cite web
   |url=http://www.bitsavers.org/pdf/dec/prism/memos/880610_OSF_on_PRISM.pdf
   |title=Internal Memo  |publisher=Digital Equipment Corporation |date=10 June 1988
   |access-date=4 December 2017}}</ref><ref>"RSX was a separate path at DEC and the progenitor more than anything of VMS that went to NT via Dave Cutler." — [[Gordon Bell]],  Vice President, Research and Development, Digital Equipment Corporation.</ref>

Under the direction of [[Ron McLean (computer scientist)|Ron McLean]] a derivative of RSX-11M, called RSX-20F, was developed to run on the PDP-11/40 front-end processor for the KL10 [[PDP-10]] CPU.<ref name=RSX20F.KL>{{cite web
|url=http://www.bitsavers.org/pdf/dec/pdp10/TOPS20/AA-H352B-TK_RSX-20F_Nov81.pdf
|title=TOPS-10/TOPS-20 RSX-20F System Reference Manual
|page=1{{hyphen}}6 |quote=For these reasons, RSX-11M was chosen as the basis for RSX-20F. |date=November 1980}}</ref>

Meanwhile, RSX-11D saw further developments: under the direction of [[Garth Wolfendale]] (project leader 1972–1976) the system was redesigned and saw its first commercial release. Support for the 22-bit PDP-11/70 system was added. Wolfendale, originally from the UK,  also set up the team that designed and prototyped the [[Interactive Application System]] (IAS)<ref name=DEChist75/> operating system in the UK; IAS was a variant of RSX-11D more suitable for [[time sharing]]. Later development and release of IAS was led  by [[Andy Wilson (computer scientist)|Andy Wilson]], in Digital's UK facilities.

===Release dates===
Below are estimated release dates for RSX-11 and IAS. Data is taken from the printing date of the associated documentation. General availability date is expected to come closely after. When manuals have different printing dates, the latest date is used. RSX-11S is a proper subset of RSX-11M, so release dates are always assumed to be the same as the corresponding version of RSX-11M. On the other side, RSX-11M Plus is an enhanced version of RSX-11M, so it is expected to be later than the corresponding version of RSX-11M.

{| class="wikitable"
|-
! Date
! RSX-11A, C
!RSX-11D
!IAS
!RSX-11M, S
!RSX-11M Plus
!Micro/RSX
! Comment
|-
| March 1973<ref>{{cite web
| url=http://www.bitsavers.org/pdf/dec/pdp11/rsx11a/RSX11A/DEC-11-IRSAA-A-D_pgmrRef_Mar73.pdf
| title=RSX 11A Programmer's Reference Manual
| author=Digital Equipment Corporation
| date=March 1973
| access-date=15 November 2022}}</ref>
| RSX-11A 1.0
|
|
|
|
|
|
|-
| May 1973<ref>{{cite web
| url=http://gordonbell.azurewebsites.net/digital/timeline/1973.htm
| title=DIGITAL Computing Timeline
| author=Digital Equipment Corporation
| date=August 1997
| access-date=10 December 2017}} Originally published on [[CD-ROM]], copy hosted on the website of [[Gordon Bell]]</ref>
|
|RSX 11D 1.0
|
|
|
|
|
|-
| December 1973<ref>Data from the labels of the distribution paper tapes. {{cite web
| url=http://www.bitsavers.org/bits/DEC/pdp11/papertapeimages/rsx11c/labels.txt
| title=RSX 11C Paper Tape Labels
| author=Digital Equipment Corporation
| date=15 December 1973
| access-date=10 December 2017}}</ref>
| RSX-11C 7A
|
|
|
|
|
| Final release of RSX-11C
|-
| November 1974<ref>General availability date. See: {{cite web
| url=http://www.bitsavers.org/pdf/dec/pdp11/rsx11m_s/RSX11M_V1/RSX-11M-V1-Task_Builder_Reference_Manual.pdf
| title=RSX 11M Task Builder Reference Manual
| author=Digital Equipment Corporation
| date=November 1974
| access-date=15 November 2022}}<br>Selected customers were testing the system at least since
June 1974, because preliminary documentation contains a standard DEC license with a 1973 copyright date. See: {{cite web
| url=http://www.bitsavers.org/pdf/dec/pdp11/rsx11m_s/RSX11M_V1/130-951-009-03_RSX-11M_Working_Design_Document_Jun74.pdf
| title=RSX 11M Working Design Document
| author=Digital Equipment Corporation
| date=June 1974
| access-date=15 November 2022}}</ref>
|
|
|
|RSX-11M 1.0
|
|
|
|-
| June 1975<ref>{{cite web
| url=http://www.bitsavers.org/pdf/dec/pdp11/rsx11d/RSX11D_V6.2_Feb77/DEC-11-OXDIA-E-D_RSX-11D_System_Generation_Manual_197702.pdf
| title=RSX-11D System Generation Reference Manual
| author=Digital Equipment Corporation
| date=February 1977
| access-date=15 November 2022}}</ref>
|
|RSX-11D 6.2
|
|
|
|
| Final version of RSX-11D
|-
| September 1975
|
|
|
|RSX-11M 2.0<br>RSX-11S 2.0
|
|
| RSX-11S 1.0 never existed
|-
| December 1975
|
|
|IAS 1.0
|
|
|
| 
|-
| April 1977
|
|
|
|RSX-11M 3.0<br>RSX-11S 3.0
|
|
|
|-
| December 1977
|
|
|
|RSX-11M 3.1<br>RSX-11S 3.1
|
|
|
|-
|May 1979
|
|
|
|RSX-11M 3.2<br>RSX-11S 3.2
|RSX-11M Plus 1.0
|
|
|-
| bef. October 1979<ref>{{cite web
| url=http://www.bitsavers.org/pdf/dec/pdp11/catalogs/AV-3468J-TC_SysSwCataOct79.pdf
| title=PDP-11 System Software Component Catalogue
| date=October 1979
| publisher=Digital Equipment Corp.
| access-date=11 December 2017}} p. 64</ref>
|
|
|IAS 3.0
|
|
|
| Final major release of IAS
|-
| November 1981
|
|
|
|RSX-11M 4.0
RSX-11S 4.0
|RSX-11M Plus 2.0
|
|
|-
|April 1983
|
|
|
|RSX-11M 4.1<br>RSX-11S 4.1
|RSX-11M Plus 2.1
|
|
|-
| July 1985
|
|
|
|RSX-11M 4.2<br>RSX-11S 4.2
|RSX-11M Plus 3.0
|Micro/RSX 3.0
|
|-
|  September 1987
|
|
|
|RSX-11M 4.3<br>RSX-11S 4.3
|RSX-11M Plus 4.0
|Micro/RSX 4.0
|  Final Micro/RSX version
|-
|May 1988
|
|
|
|RSX-11M 4.4<br>RSX-11S 4.4
|RSX-11M Plus 4.1
|
|
|-
|January 1989
|
|
|
|RSX-11M 4.5<br>RSX-11S 4.5
|RSX-11M Plus 4.2
|
|
|-
|January 1990
|
|
|
|RSX-11M 4.6<br>RSX-11S 4.6
|RSX-11M Plus 4.3
|
|
|-
| May 1990<ref name="final_IAS">{{cite web
| url=http://www.bitsavers.org/pdf/dec/pdp11/ias/v3.4/IAS_3.4A_SPD_May1990.pdf
| title=IAS Version 3.4 Software Product Description
| author=Digital Equipment Corporation
| date=May 1990
| access-date=6 December 2017}}</ref>
|
|
|IAS 3.4
|
|
|
|  Final IAS Release
|-
| February 1993
|
|
|
|RSX-11M 4.7<br>RSX-11S 4.7
|RSX-11M Plus 4.4
|
|  Last release from Digital Equipment
|-
|March 1995
|
|
|
|
|RSX-11M Plus 4.5
|
|
|-
|November 1998
|
|
|
|RSX-11M 4.8<br>RSX-11S 4.8
|
|
|Released by Mentec
|- 
|  February 1999
|
|
|
|
|RSX-11M Plus 4.6
|Micro/RSX 4.6
|  Released by Mentec 
|}

===Legal ownership, development model and availability===
RSX-11 is [[proprietary software]]. [[Copyright]] is asserted in binary files, source code and documentation alike. It was entirely developed internally by Digital. Therefore, no part of it is [[open-source software|open source]]. However a copy of the kernel source is present in every RSX distribution, because it was used during the [[system generation]] process. The notable exception to this rule is Micro-RSX, which came with a pre-generated autoconfiguring binary kernel. Full sources was available as a separate product to those who already had a binary license, for reference purposes.

Ownership of RSX-11S, RSX-11M, RSX-11M Plus and Micro/RSX was transferred from Digital to [[Mentec PDP-11|Mentec Inc.]] in March 1994<ref>{{cite web| url=http://www.bitsavers.org/pdf/dec/pdp11/rsx11m_s/SPD/AV-QKPJA-TE_Notice_of_Copyright_Change_for_PDP-11_Software_Products_1995.pdf| title=Notice of Copyright Change for PDP-11 Software Products| author=Mentec Inc.| date=1995| access-date=15 November 2022}}</ref> as part of a broader agreement.<ref>{{cite web| url=https://groups.google.com/forum/#!topic/biz.digital.announce/mnNlxqdYTwo| title=Press release: Digital and Mentec announce PDP-11 Software Agreement| author=Digital Equipment Corporation| date=29 June 1994| access-date=11 December 2017}}</ref>
Mentec Inc. was the US subsidiary of [[Mentec PDP-11|Mentec Limited]], an Irish firm specializing in PDP-11 hardware and software support. In 2006 Mentec Inc. was declared bankrupt while Mentec Ltd. was acquired by Irish firm Calyx in December 2006.<ref>{{cite web| url=https://www.theregister.co.uk/2006/12/13/calyx_buys_mentec/| title=Calyx buys Mentec| author=Mentec Inc.| website=[[The Register]]| date=13 December 2006| access-date=11 December 2017}}</ref> The PDP-11 software, which was owned by Mentec Inc. was then bought by XX2247 LLC, which is the owner of the software today.{{Citation needed|date=November 2022}} It is unclear if new commercial licenses are possible to buy at this time. Hobbyists can run RSX-11M (version 4.3 or earlier) and RSX-11M Plus (version 3.0 or earlier) on the [[SIMH]] emulator thanks to a free license granted in May 1998 by Mentec Inc.<ref>{{cite web| url=https://www.eecis.udel.edu/~mader/delta/download/license.txt| title=Mentec Hobbyist license for PDP-11 operating systems| author=Mentec Inc.| date=May 1998| access-date=11 December 2017}}</ref>

Legal ownership of RSX-11A, RSX-11B, RSX-11C, RSX-11D, and IAS never changed hands; therefore it passed to [[Compaq]] when it acquired Digital in 1998<ref>{{cite web| url=https://www.cnet.com/news/compaq-to-buy-digital-for-9-6-billion/| title=Compaq to buy Digital for $9.6 billion| author=Michael Kanellos| date=26 January 1998| publisher=cnet.com| access-date=11 December 2017}}</ref> and then to [[Hewlett-Packard]] in 2002.<ref>{{cite web| url=https://www.cnet.com/news/hp-to-acquire-compaq-for-25-billion/| title=HP to acquire Compag for $25 billion| author=Michael Kanellos| date=10 March 2002| publisher=cnet.com| access-date=11 December 2017}}</ref> In late 2015 Hewlett-Packard split into two separate companies ([[HP Inc.]] and [[Hewlett Packard Enterprise]]),<ref>{{cite web| url=https://www.recode.net/2015/11/2/11620238/hewlett-packard-splits-in-two-today-now-what| title=Hewlett-Packard splits in two today, now what ?| author=Arik Hesseldahl| date=2 November 2015| publisher=recode.net| access-date=11 December 2017}}</ref> so the current owner cannot be firmly established.{{dubious|date=June 2020}} No new commercial licenses have been issued since at least October 1979 (RSX-11A, RSX-11B, RSX-11C)<ref>Products no longer appeared on Digital PDP-11 System Software Catalogue issued Oct. 1979: {{cite web| url=http://www.bitsavers.org/pdf/dec/pdp11/catalogs/AV-3468J-TC_SysSwCataOct79.pdf| title=PDP-11 System Software Component Catalogue| date=October 1979| publisher=Digital Equipment Corp.| access-date=11 December 2017}}</ref> or 1990 (IAS),<ref name="final_IAS" /> and none of these operating systems have ever been licensed for hobbyist use.