Editing RT-11 (section)

==Versions==

===Variants===
Users could choose from variants with differing levels of support for [[Computer multitasking|multitasking]], memory size, and separate I & D (Instruction and Data) address space:
====Unmapped memory====
* '''RT-11SJ''' (Single Job) allowed only one task. This was the initial distribution.
* '''RT-11BL''' (Base-line) a stripped down version of SJ that has minimal memory residency and lacks optional features.<ref>{{cite book |author=<!--Staff writer(s); no by-line.--> |url=https://archive.org/details/bitsavers_decpdp11rtATCRT11V4.0InstallationManualMar81_19001358 |title=RT-11 Installation and System Generation Guide |date=March 1980 |publisher=Digital Equipment Corporation |isbn= |location=Maynard, MA |page=1-6}}</ref>
* '''RT-11FB''' (Foreground/Background) supported two tasks: a high-priority, non-interactive "Foreground" job, and a low-priority, interactive "Background" job.<ref name=RT11.HC82Decem/>
====Mapped memory====
* '''RT-11XB''' single job, does not support I & D separation.<ref name=RT_install>{{cite book |author=<!--Staff writer(s); no by-line.--> |date=August 1991 |title=RT-11 Installation Guide |url=http://www.bitsavers.org/pdf/dec/pdp11/rt11/v5.6_Aug91/AA-H376F-TC_RT-11_Installation_Guide_Aug91.pdf |location=Maynard, Massachusetts |publisher=Digital Equipment Corporation |pages=1-2,1-3 |isbn=}}</ref>
* '''RT-11XM''' (eXtended Memory), a superset of FB,<ref name=RT11.HC82Decem/> provided support for memory beyond 64kb, but required a minicomputer with memory management hardware; distributed from approx. 1975-on. Up to 8 concurrent jobs.<ref name=RT_install />
* '''RT-11ZB''' single job, supports I & D separation.<ref name=RT_install />
* '''RT-11ZM''' provided support for systems with Separate Instruction and Data space (such as on the [[Unibus]]-based 11/44, 45, 55, 70, 84, and 94 and the [[Q-Bus]]-based 11/53, [[PDP-11/73|73]], 83, and 93.) Up to 8 concurrent jobs.<ref name=RT_install />

===Specialized versions===
Several specialized PDP-11 systems were sold based on RT-11:

* LAB-11 provided an LPS-11 analog peripheral for the collection of laboratory data
* PEAK-11 provided further customization for use with [[gas chromatograph]]s (analyzing the peaks produced by the GC); data collection ran in RT-11's foreground process while the user's data analysis programs ran in the background.
* GT4x systems added a VT11 vector graphics peripheral. Several very popular demo programs were provided with these systems including [[Lunar Lander (1979 video game)|Lunar Lander]] and a version of [[Spacewar!]].
* GT62 systems added a VS60 vector graphics peripheral (VT11-compatible) in a credenza cabinet.
* GAMMA-11 was a packaged RT-11 and PDP 11/34 system that was one of the first fully integrated Nuclear Medicine systems. It included fast analog/digital converters, 16 bit colour graphical displays, and an extensive software library for development of applications for the purpose of data collection, analysis and display from a [[nuclear medicine]] [[gamma camera]].

===Clones in the USSR===
<!-- Deleted image removed: [[File:osbk11.png|256px|thumb|[[Elektronika BK|BK-0011M]] running OS BK-11 and Inter Commander file manager]] -->
Several clones of RT-11 were made in the USSR:

* [[RAFOS (operating system)|RAFOS]] (РАФОС) – [[SM EVM]]
* [[FOBOS]] (ФОБОС) – [[Elektronika 60]]
* [[FODOS]] (ФОДОС)
* [[RUDOS]] (РУДОС)
* [[OS DVK]] (ОС ДВК) – [[DVK]]
* [[OS BK-11]] (ОС БК-11) – [[Elektronika BK]]
* [[MASTER-11]] (МАСТЕР-11) – [[DVK]]
* NEMIGA OS (НЕМИГА) – Nemiga PK 588