RT-11 ('RT' for
Real Time) was a small, single-user
real-time operating systemA real-time operating system is a multitasking operating system intended for real-time applications. Such applications include embedded systems , industrial robots, spacecraft, industrial control , and scientific research equipment.A RTOS facilitates the creation of a real-time system, but does not...
for the
Digital Equipment CorporationDigital Equipment Corporation was a pioneering American company in the computer industry. It is often referred to within the computing industry as DEC...
PDP-11The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corp. from 1970 into the 1990s. Though not explicitly conceived as successor to DEC's PDP-8 computer in the PDP series of computers , the PDP-11 replaced the PDP-8 in many real-time applications...
family of 16-bit computers. RT-11 was first implemented in 1970 and was widely used for
real-timeIn computer science, real-time computing , or "reactive computing", is the study of hardware and software systems that are subject to a "real-time constraint"—i.e., operational deadlines from event to system response. By contrast, a non-real-time system is one for which there is no deadline, even...
systems,
process controlProcess control is a statistics and engineering discipline that deals with architectures, mechanisms, and algorithms for controlling the output of a specific process. See also control theory....
, and
data acquisitionIn computer data processing, data acquisition is the sampling of real world physical conditions and conversion of the resulting samples into digital numeric values that can be manipulated by a computer...
across the full line of PDP-11 computers.
Multitasking
RT-11 systems did not support
preemptive multitaskingIn computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions...
, but most versions could run multiple simultaneous applications. All variants of the monitors provided a
Background Job. The FB, XM and ZM monitors also provided a
Foreground Job, as well as six
System Jobs if selected via the SYSGEN System Generation program. These tasks had fixed priorities, with the
Background Job lowest and the
Foreground Job highest. It was possible to switch between jobs from the
system consoleThe system console, root console or simply console is the text entry and display device for system administration messages, particularly those from the BIOS or boot loader, the kernel, from the init system and from the system logger...
user interface, and SYSGEN could generate a monitor that provided a single
Background Job (the SB, XB and ZB variants).
Source code
RT-11 was written in
assembly languageAssembly languages are a family of low-level languages for programming computers, microprocessors, microcontrollers, and other integrated circuits. They implement a symbolic representation of the numeric machine codes and other constants needed to program a particular CPU architecture...
. Heavy use of the conditional assembly and macro programming features of the
MACRO-11MACRO-11 is an assembly language with macro facilities for PDP-11 minicomputers from Digital Equipment Corporation . It is the successor to PAL-11 , an earlier version of the PDP-11 assembly language without macro facilities....
assembler allowed a significant degree of configurability and allowed programmers to specify high-level instructions otherwise unprovided for in machine code. RT-11 distributions included the
source codeIn computer science, source code is any collection of statements or declarations written in some human-readable computer programming language...
of the operating system and its device drivers with all the comments removed and a program named "SYSGEN" which would build the operating system and drivers according to a user-specified configuration. Developer's documentation included a
kernelIn computing, the 'kernel' is the central component of most computer operating systems. Its responsibilities include managing the system's resources...
listing that included comments.
Device drivers
In early versions of RT-11,
device driverIn computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....
s were built into the kernel at configuration time, but in later versions the device drivers were loadable. Because RT-11 was commonly used for device control and data acquisition, it was common for developers to write or enhance device drivers. DEC encouraged such driver development by making their hardware subsystems (from bus structure to code) open, documenting the internals of the operating system, encouraging third-party hardware and software vendors, and by fostering the development of the
Digital Equipment Computer Users SocietyDECUS was an independent computer user group related to Hewlett-Packard and HP Partners.The Connect User Group Community, formed from the consolidation in May, 2008 of DECUS, Encompass, HP-Interex, and ITUG is Hewlett-Packard’s largest user community representing more than 50,000...
.
Human interface
Users generally operated RT-11 via a printing terminal or a
video terminalA computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
, originally via a strap-selectable current-loop (for conventional teletypes) or
RS-232In telecommunications, RS-232 is a standard for serial binary data signals connecting between a
DTE and a
DCE . It is commonly used in computer serial ports...
(later
RS-422American national standard ANSI/TIA/EIA-422-B and its international equivalent ITU-T Recommendation , are technical standards that specify the "electrical characteristics of the balanced voltage digital interface circuit"...
as well) interface on one of the CPU cards; DEC also supported the VT11 and VS60 graphics display devices (
vector graphicsVector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon, which are all based on mathematical equations, to represent images in computer graphics....
terminalA monitor or display is a piece of electrical equipment which displays images generated by devices such as computers, without producing a permanent record. The monitor comprises the display device, circuitry, and an enclosure...
s with a graphic character generator for displaying text, and a
light penA light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy...
for graphical input). A third-party favorite was the Tektronix 4010 family.
The Keyboard Monitor (KMON) interpreted commands issued by the user and would invoke various utilities with Command String Interpreter (CSI) forms of the commands.
RT-11 command language had many features (such as commands and device names) that can be found later in
DOSDOS, short for "Disk Operating System", is a shorthand term for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions Windows 95, 98, and ME.Related systems...
line of operating systems which heavily borrowed from RT-11. The CSI form expected input and output
filenameA filename is a special kind of string used to uniquely identify a file stored on the file system of a computer. Some operating systems also identify directories in the same way. Different operating systems impose different restrictions on length and allowed characters on filenames...
s and options ('switches' on RT-11) in a precise order and syntax. The command-line switches were separated by "/" sign rather than "-" used in
Unix-likeA Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating systems. All commands had full form and a short one to which it could be contracted. For example, RENAME command could be contracted to
RENIn computing, ren is a command in various DOS, OS/2 and Microsoft Windows command line interpreters such as COMMAND.COM, cmd.exe, 4DOS/4NT and Windows PowerShell. It is used to rename files and in some implementations also directories. It is analogous to the...
.
Batch files and the batch processor could be used to issue a series of commands with some rudimentary
flow controlIn computer networking, flow control is the process of managing the rate of data transmission between two nodes to prevent a fast sender from outrunning a slow receiver. It provides a mechanism for the receiver to control the transmission speed, so that the receiving node is not overwhelmed with...
. Batch files had the
extensionA filename extension is a suffix to the name of a computer file applied to indicate the encoding convention of its contents.In some operating systems it is optional, while in some others it is a requirement...
.BAT.
In later releases of RT-11, it was possible to invoke a series of commands using a .COM command file, but they would be executed in sequence with no flow control. Even later, it was possible to execute a series of commands with great control through use of the Indirect Command File Processor (IND), which took .CMD control files as input.
Files with the extension .SAV were executables. They were known as "sav files" because the RT-11 SAVE command could be used to save the contents of memory to a disk file which could be loaded and executed at a later time.
The SAVE command, along with GET, START, REENTER, EXAMINE and DEPOSIT are basic commands implemented in the KMON. Some commands and utilities were later borrowed in
DOSDOS, short for "Disk Operating System", is a shorthand term for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions Windows 95, 98, and ME.Related systems...
-line of operating systems. These commands include DIR,
COPYIn computing, copy is a command in RT-11, RSX-11, OpenVMS, DOS, OS/2 and Microsoft Windows operating systems. The command copies computer files from one directory to another. The destination defaults to the current working directory. If more than one source file is indicated, the...
,
RENAMERename is a word meaning change the name of something. Different areas, such as linguistics, relational algebra, and computer science incur renaming actions with different detailed activity, however the principles behind are all the same — change the name of something.Specific uses:* Rename...
, ASSIGN,
CLScls is a command used by the command line interpreters COMMAND.COM and cmd.exe on DOS, OS/2 and Microsoft Windows operating systems to clear the screen or console window of commands and any output generated by them. It does not clear the user's history of commands, however...
, DELETE,
TYPEIn computing, type is a command in various VMS, CP/M, DOS, OS/2 and Microsoft Windows command line interpreters such as COMMAND.COM, cmd.exe, 4DOS/4NT and Windows PowerShell. It is used to display the contents of specified files...
,
HELPIn computing, help is a command in various command line shells such as COMMAND.COM, cmd.exe, 4DOS/4NT, Windows PowerShell, Singularity shell, Python and GNU Octave. It provides online information about available commands and the shell environment...
and others. FORMAT command was used for physical disk formatting, although it was not capable of creating file system, for which purpose INIT command was used (analogue of DOS command FORMAT /Q). Most commands supported use of
wildcards-Telecommunication:In telecommunications, a wildcard character is a character that may be substituted for any of a defined subset of all possible characters....
in file names.
Physical device names were specified in the form 'dd{n}:' where 'dd' was a two-character alphabetic device name and the optional 'n' was the unit number (0-7). When the unit number is omitted, unit 0 is assumed. For example, TT: referred to the console terminal, LP: (or LP0:) referred to the parallel line printer, and DX0:, DY1:, DL4: referred to disk volumes (RX01 unit 0, RX02 unit 1, RL01 or RL02 unit 4, respectively). Logical device names consisted of 1-3 alphanumeric characters and were used in the place of a physical device name. This was accomplished using the
ASSIGN command. For example, one might issue
ASSIGN DL0 ABC which would cause all future references to 'ABC:' to map to 'DL0:'. Reserved logical name DK: referred to the current default device. If a device was not included in a file specification, DK: was assumed. Reserved logical name SY: referred to the system device (the device from which the system had been booted).
Later versions of RT-11 allowed specification of up to 64 units (0-77 octal) for certain devices, but the device name was still limited to three alphanumeric characters. This feature was enabled through a SYSGEN selection, and only applied to the DU and LD device handlers. In these two cases, the device name form became 'dnn:' where 'd' was 'D' for the DU device and 'L' for the LD device, and 'nn' was 00-77(octal).
Software
RT-11 was distributed with utilities which allowed a user to perform many actions. The utilities
DIR,
DUP,
PIP and
FORMAT allowed a user to manage their disk volumes.
TECOTECO is a text editor originally developed at the Massachusetts Institute of Technology in the 1960s, after which it was modified by 'just about everybody'...
,
EDIT, and the
visual editorVisual editors are editing programs which display the text being edited on the screen as it is being edited, as opposed to line-oriented editors .The term is generally used in discussing character mode, as opposed to GUI applications...
s
KED (for the DEC
VT100VT100 is a video terminal which was made by Digital Equipment Corporation . It became the de facto standard used by terminal emulators....
) and
K52 (for the DEC
VT52The VT52 was a CRT-based computer terminal produced by Digital Equipment Corporation during the late 1970s. It provided a screen of 24 rows and 80 columns of text and supported all 95 ASCII characters as well as 32 graphics characters. It supported asynchronous communication at baud rates up to...
) allowed a user to create and edit source and data files.
MACRO,
LINK, and
LIBR allowed a user to build their own executables.
ODTOctal Debugging Technique, or ODT, was the name of several debugger programs originally developed for DEC hardware. Various operating systems including OS/8, RT-11, RSX-11, and RSTS/E implemented ODT as did the firmware console of all of the LSI-11-family processors including the 11/03, 11/23/24,...
,
VDT and the SD device allowed a user to debug programs. DEC's version of
Runoffrunoff was the text formatting program on the Multics operating system.It was a descendant of the RUNOFF type-setting program from CTSS and was originally written by Jerome H. Saltzer...
allowed a user to produce documents. Finally, VTCOM allowed a user to connect with and use (or transfer files to and from) another computer system over the phone using a modem.
The system was complete enough to handle many modern personal computing tasks. Large amounts of free, user-contributed software for RT-11 were available from the
Digital Equipment Computer Users SocietyDECUS was an independent computer user group related to Hewlett-Packard and HP Partners.The Connect User Group Community, formed from the consolidation in May, 2008 of DECUS, Encompass, HP-Interex, and ITUG is Hewlett-Packard’s largest user community representing more than 50,000...
including an implementation of
CC is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
. Although the tools to develop and debug assembly-language programs were provided, other languages including C,
FortranFortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
,
PascalPascal is an influential imperative and procedural programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.A derivative known as Object Pascal...
, and several versions of
BASICIn computer programming, BASIC is a family of high-level programming languages. The original BASIC was designed in 1964 by John George Kemeny and Thomas Eugene Kurtz at Dartmouth in New Hampshire, USA to provide computer access to non-science students...
were available from DEC as "layered products" at extra cost. Versions of these and other programming languages were also available from other, third-party, sources. It is even possible to network RT-11 machines using
DECNETDECnet is a suite of network protocols created by Digital Equipment Corporation, originally released in 1975 in order to connect two PDP-11 minicomputers...
, the
InternetThe Internet Protocol Suite is the set of communications protocols used for the Internet and other similar networks. It is named from two of the most important protocols in it: the Transmission Control Protocol and the Internet Protocol , which were the first two networking protocols defined in...
and protocols developed by other, third-party sources.
Distributions and Minimal system configuration
The RT-11 operating system could be booted from, and actually perform useful work on, a machine consisting of two 8-inch 250kb
floppy diskA floppy disk is a data storage medium that is composed of a disk of thin, flexible magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive or FDD, the initials of which should not be confused with "fixed disk drive," which...
s and 64K of memory, and could actually support 4 terminals. Other boot options include a 2.5MB removable hard disk platter (RK05), or
magnetic tapeMagnetic tape is a medium for magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of plastic. Nearly all recording tape is of this type, whether used for recording audio or video or for computer data storage. It was originally developed in Germany,...
. Distributions were available pre-installed or on
punched tapePunched tape or paper tape is a largely obsolete form of data storage, consisting of a long strip of paper in which holes are punched to store data...
, magnetic tape, cartridge tape, or floppy disk. A minimal but complete system supporting a single real-time user could run on a 5MB hard disk and in 8K 16-bit words (16KB) of RAM, including user programs. The system supported a
real-time clockA real-time clock is a computer clock that keeps track of the current time. Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are present in almost any electronic device which needs to keep accurate time.-Terminology:The term is used to avoid...
, printing terminal, VT11 vector graphic unit, 16 channel 100 kHz A/D converter with 2 channel D/A, 9600 baud serial port, 16 bit bidirectional boards, etc.
File system
RT-11 implemented a simple and fast
file systemIn computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them...
employing filenames with six characters and three-character extensions ("6.3" vs. the
MS-DOSMS-DOS is an operating system developed by Microsoft. It was the most commonly used member of the DOS family of operating systems and was the main operating system for personal computers during the 1980s. It was preceded by M-DOS , designed and copyrighted by Microsoft in 1979...
8.3 filename format) encoded in
RADIX-50RADIX-50, commonly called Rad-50 or RAD50, is a character encoding created by Digital Equipment Corporation for use on their DECsystem, PDP, and VAX computers...
, which packed those 9 characters into only six bytes (three 16-bit words). All files were contiguous, meaning that each file occupied consecutive blocks (the minimally addressable unit of disk storage, 512 bytes) on the disk. This meant that an entire file could be read (or written) very quickly. A side effect of this file system structure was that as files were created and deleted on a volume over time, the unused disk space became fragmented and a disk would need to be periodically 'squeezed' to consolidate the unused portions. The practice of 'squeezing' a volume continues today under
WindowsMicrosoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces...
and other operating systems through a process called
defragmentationIn the context of administering computer systems, defragmentation is a process that reduces the amount of fragmentation in file systems. It does this by physically organizing the contents of the disk to store the pieces of each file close together and contiguously. It also attempts to create larger...
.
Compatibility with other DEC operating systems
Many RT11 programs (those that did not need specialized peripherals or direct access to the hardware) could be directly executed using the RT11 RTS (
Run-time systemA run-time system is a collection of software designed to support the execution of computer programs written in some computer language...
) of the
RSTS/ERSTS is a multi-user time-sharing operating system, developed by Digital Equipment Corporation , for the PDP-11 series of 16-bit minicomputers. The first version of RSTS was implemented in 1970 by DEC software engineers that developed the TSS-8 time-sharing operating system for the PDP-8...
timesharing system or under RTEM (RT Emulator) on various releases of both RSX-11 and
VMSOpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is the name of a high-end computer server operating system that runs on VAX, Alpha and Itanium-based families of computers...
.
The implementation of
DCLDCL, the DIGITAL Command Language, is the standard command languageadopted by most of the operating systems that were sold by the former Digital Equipment Corporation...
for RT-11 increased its compatibility with the other DEC operating systems. Although each operating system had commands and options which were unique to that operating system, there were a number of commands and command options which were common.
Other PDP-11 operating systems
DEC also sold
RSX-11RSX-11 is a family of real-time operating systems mainly for PDP-11 computers created by Digital Equipment Corporation , common in the late 1970s and early 1980s. RSX-11D first appeared on the PDP-11/40 in 1972...
, a multiuser, multitasking operating system with realtime features, and
RSTS-11RSTS is a multi-user time-sharing operating system, developed by Digital Equipment Corporation , for the PDP-11 series of 16-bit minicomputers. The first version of RSTS was implemented in 1970 by DEC software engineers that developed the TSS-8 time-sharing operating system for the PDP-8...
a multiuser time-sharing system, but RT-11 remained the operating system of choice for
data acquisitionIn computer data processing, data acquisition is the sampling of real world physical conditions and conversion of the resulting samples into digital numeric values that can be manipulated by a computer...
systems where real time response was required. The
UnixUnix is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
operating system also became popular, but lacked the real-time features and extremely small size of RT-11.
Hardware
RT-11 ran on all members of the DEC PDP-11 family, both
Q-BusThe Q-bus was one of several bus technologies used with PDP and MicroVAX computer systems manufactured by the Digital Equipment Corporation of Maynard, Massachusetts....
- and
UnibusThe Unibus was the earliest of several bus technologies used with PDP-11 and early VAX systems manufactured by the Digital Equipment Corporation of Maynard, Massachusetts....
-based, from the PDP-11/05 (its first target, in 1970), to the final PDP-11 implementations (PDP-11/93 and /94). In addition, it ran on the Professional Series and the PDT-11 "Programmed Data Terminal" systems, also from DEC. Since the PDP-11 architecture was implemented in replacement products by other companies (Eg, the M100 and family from Mentec), or as reverse-engineered clones in other countries (Eg, the
DVKDVK is a Soviet PDP-11-compatible personal computer.The design is also known as Elektronika MS-0501 and Elektronika MS-0502....
from the Soviet Union), RT-11 runs on these machines as well.
Fuzzball
FuzzballFuzzball routers were the first modern routers on the Internet. They were DEC LSI-11 computers loaded with router software written by David L. Mills . The name "Fuzzball" was the colloquialism for Mills' routing software. About fifty of them were deployed worldwide in the early 1980s on the first...
, routing software for
Internet ProtocolThe Internet Protocol is a protocol used for communicating data across a packet-switched internetwork using the Internet Protocol Suite, also referred to as TCP/IP....
s, was capable of running RT-11 programs.
TSX-11
S&H Computing developed and distributed
TSX-PlusTSX-Plus is a multi-user operating system for the PDP-11/LSI-11 series of computers. It was developed by S&H Computer Systems, Inc. and is based on DEC's RT-11 single-user real-time operating system...
, a multi-user, multi-processing implementation of RT-11. The only thing it didn't do was handle the boot process, so any TSX-Plus machine was required to boot RT-11 first before running TSX-Plus as a user program. Once TSX-Plus was running, it would take over complete control of the machine from RT-11. It provided true memory protection for users from other users, provided user accounts and maintained account separation on disk volumes and implemented a superset of the RT-11 EMT programmed requests. RT-11 programs generally ran, unmodified, under TSX-Plus and, in fact, most of the RT-11 utilities were used as-is under TSX-Plus. Device drivers generally required only slight modifications.
Release history
| Version | Release date | Notes |
|---|
| RT-11 |
July 1973 |
|
| RT-11 v2 |
1974 |
|
| RT-11 v2C |
1976 |
|
| RT-11 v3 |
1977 |
|
| RT-11 4 |
21 February 1980 |
|
| GAMMA-11 |
1980? |
|
| RT-11 5.0.3 |
Late 1982? |
|
| RT-11 5.1 |
1984 |
|
| RT-11 5.2 |
1985 |
|
| RT-11 5.3 |
1986 |
|
| RT-11 5.4 |
August 1986? |
|
| RT-11 5.5 |
? |
|
| RT-11 5.6 |
October 1992? |
|
| RT-11 5.7 |
29 October 1998 |
|
Variants
Users could choose from four variants with differing levels of support for
multitaskingIn computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions...
:
- RT-11SJ (Single Job) allowed only one task. This was the initial distribution.
- RT-11FB (Foreground/Background) supported two tasks: a high-priority, non-interactive "Foreground" job, and a low-priority, interactive "Background" job.
- RT-11XM (eXtended Memory) provided support for memory beyond 64kb, but required a minicomputer with memory management hardware; distributed from approx. 1975-on.
- RT-11ZM provided support for systems with Separate Instruction and Data space (such as on the Unibus
The Unibus was the earliest of several bus technologies used with PDP-11 and early VAX systems manufactured by the Digital Equipment Corporation of Maynard, Massachusetts....
-based 11/44, 45, 55, 70, 84, and 94 and the Q-BusThe Q-bus was one of several bus technologies used with PDP and MicroVAX computer systems manufactured by the Digital Equipment Corporation of Maynard, Massachusetts....
-based 11/53, 73, 83, and 93)
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 chromatographs (analyzing the peaks produced by the GC); data collection ran in RT11'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
Lunar Lander is the name of several video games. In all variations of the game, the player must portion a limited amount of fuel to land on the moon without crashing...
and a version of Spacewar!.
- 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
Nuclear medicine is a branch or specialty of medicine and medical imaging that uses radioactive isotopes and relies on the process of radioactive decay in the diagnosis and treatment of disease. In nuclear medicine procedures, radionuclides are combined with other chemical compounds or...
gamma cameraA gamma camera is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy. The applications of scintigraphy include early drug development and nuclear medical imaging to view and analyse images of the human body or the distribution of medically injected,...
.
Clones in the USSR
Several clones of RT-11 were made in the USSR:
- RAFOS ("РАФОС") — SM EVM
SM EVM was general name for several types of Soviet and Comecon minicomputers in 1970s and 1980s.Production started in 1975.Most types of SM EVM have been clones of DEC PDP-11 and VAX.The common operating system was MOS, a clone of UNIX....
- FOBOS ("ФОБОС") — Elektronika 60
- FODOS ("ФОДОС")
- RUDOS ("РУДОС")
- OS DVK ("ОС ДВК") — DVK
DVK is a Soviet PDP-11-compatible personal computer.The design is also known as Elektronika MS-0501 and Elektronika MS-0502....
- OS BK-11 ("ОС ВК-11") — Elektronika BK
The Elektronika BK was a series of 16-bit PDP-11-compatible Soviet home computers developed by NPO Scientific Center, the leading Soviet microcomputer design team at the time. It was also responsible also for the more powerful UKNC and DVK micros...
- MASTER-11 ("МАСТЕР-11") — DVK
DVK is a Soviet PDP-11-compatible personal computer.The design is also known as Elektronika MS-0501 and Elektronika MS-0502....
External links