RT-11

RT11
RT-11 ("RT" for real-time) is a discontinued small, single-user real-time operating system for the Digital Equipment Corporation PDP-11 family of 16-bit computers.wikipedia
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Real-time computing

real-timereal timereal-time systems
RT-11 was first implemented in 1970 and was widely used for real-time systems, process control, and data acquisition across the full line of PDP-11 computers.
Minicomputers, particularly in the 1970s onwards, when built into dedicated embedded systems such as DOG scanners, increased the need for low-latency priority-driven responses to important interactions with incoming data and so operating systems such as Data General's RDOS (Real-Time Disk Operatings System) and RTOS with background and foreground scheduling as well as Digital Equipment Corporation's RT-11 date from this era.

Digital Equipment Corporation

DECDigitalDigital Equipment
RT-11 ("RT" for real-time) is a discontinued small, single-user real-time operating system for the Digital Equipment Corporation PDP-11 family of 16-bit computers.

PDP-11

LSI-11PDP-11/70DEC PDP-11
RT-11 ("RT" for real-time) is a discontinued small, single-user real-time operating system for the Digital Equipment Corporation PDP-11 family of 16-bit computers.
As the design was intended to avoid software exchange with existing PDP-11 models, their ill fate in the market was no surprise for anyone except DEC. The RT-11 operating system was eventually ported to the PRO series.

Copy (command)

COPYCOP
These commands include DIR, COPY, RENAME, ASSIGN, CLS, DELETE, TYPE, HELP and others.
The command is available in DEC RT-11, RSX-11, OS/8, Intel ISIS-II, iRMX 86, DEC TOPS-10, TOPS-20, OpenVMS, MetaComCo TRIPOS, Microware OS-9, DOS, DR FlexOS, IBM/Toshiba 4690 OS, HP MPE/iX, IBM OS/2, Microsoft Windows, ReactOS, SymbOS and DexOS.

TYPE (DOS command)

TYPEMOS
These commands include DIR, COPY, RENAME, ASSIGN, CLS, DELETE, TYPE, HELP and others.
The command is available in the operating systems DEC RT-11, OS/8, TOPS-10, TOPS-20, VMS, Digital Research CP/M, MP/M, MetaComCo TRIPOS, AmigaDOS, DOS, FlexOS, TSL PC-MOS, SpartaDOS X, IBM/Toshiba 4690 OS, IBM OS/2, Microsoft Windows, ReactOS, AROS, and SymbOS.

Ren (command)

RENAMEREN REN
These commands include DIR, COPY, RENAME, ASSIGN, CLS, DELETE, TYPE, HELP and others. For example, RENAME command could be contracted to REN.
Stratus OpenVOS, DEC RT-11, RSX-11, OS/8, Intel ISIS-II, iRMX 86, TOPS-20, Zilog Z80-RIO, TSC FLEX, Microware OS-9, DR FlexOS, IBM/Toshiba 4690 OS, HP MPE/iX, THEOS/OASIS, and OpenVMS also provide the command which in some cases can be contracted to.

CLS (command)

CLSCLS (BASIC command)CLS (DOS command)
These commands include DIR, COPY, RENAME, ASSIGN, CLS, DELETE, TYPE, HELP and others.
The command is also available in the DEC RT-11 operating system, in the open-source MS-DOS emulator DOSBox and in the EFI shell.

On-line Debugging Tool

ODTOctal Debugging Technique
ODT, VDT and the SD device allowed a user to debug programs.
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, 11/53, 11/73, and 11/83/84.

Start (command)

STARTstart.exe
The SAVE command, along with GET, START, REENTER, EXAMINE and DEPOSIT are basic commands implemented in the KMON.
The command is also one of the basic commands implemented in the Keyboard Monitor (KMON) of the DEC RT-11 operating system.

Dir (command)

DIRDIRECTORY DIR
These commands include DIR, COPY, RENAME, ASSIGN, CLS, DELETE, TYPE, HELP and others. The utilities DIR, DUP, PIP and FORMAT allowed a user to manage their disk volumes.
The command is available in the command-line interface (CLI) of the operating systems DR CP/M, MP/M, Intel ISIS-II, iRMX 86, MetaComCo TRIPOS, DOS, IBM/Toshiba 4690 OS, IBM OS/2, Microsoft Windows, Singularity, ReactOS, AROS, and in the DCL command-line interface used on DEC VMS, RT-11 and RSX-11.

Del (command)

DELERASEDELETE
These commands include DIR, COPY, RENAME, ASSIGN, CLS, DELETE, TYPE, HELP and others.
DEC RT-11, RSX-11, OS/8 and OpenVMS also provide the command which can be contracted to.

MACRO-11

Heavy use of the conditional assembly and macro programming features of the MACRO-11 assembler allowed a significant degree of configurability and allowed programmers to specify high-level instructions otherwise unprovided for in machine code.
A complete "Hello, world!" program in PDP-11 macro assembler, to run under RT-11:

Teleprinter

teletypeteletypewritertelex
Users generally operated RT-11 via a printing terminal or a video terminal, originally via a strap-selectable current-loop (for conventional teletypes) or RS-232 (later RS-422 as well) interface on one of the CPU cards; DEC also supported the VT11 and VS60 graphics display devices (vector graphics terminals with a graphic character generator for displaying text, and a light pen for graphical input).
In early operating systems such as Digital's RT-11, serial communication lines were often connected to teleprinters and were given device names starting with tt.

TYPSET and RUNOFF

RUNOFFRUNOFF commandCTSS RUNOFF
DEC's version of Runoff allowed a user to produce documents.
Other versions of Runoff were developed for various computer systems including Digital Equipment Corporation's PDP-11 minicomputer systems running RT-11, RSTS/E, RSX on Digital's PDP-10 and for OpenVMS on VAX minicomputers, as well as UNIVAC Series 90 mainframes using the EDT text editor under the VS/9 operating system.

Help (command)

HELP.Help
These commands include DIR, COPY, RENAME, ASSIGN, CLS, DELETE, TYPE, HELP and others.
The command is available in operating systems such as DOS, IBM OS/2, Microsoft Windows, ReactOS, THEOS/OASIS, Zilog Z80-RIO, Microware OS-9, Stratus OpenVOS, HP MPE/iX, Motorola VERSAdos, KolibriOS and also in the DEC RT-11, TOPS-10 and TOPS-20 operating systems.

Format (command)

FORMATFORMAT command
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). The utilities DIR, DUP, PIP and FORMAT allowed a user to manage their disk volumes.
The command is also available in Intel ISIS-II, iRMX 86, MetaComCo TRIPOS, AmigaDOS, Microware OS-9, DR FlexOS, TSL PC-MOS, SpartaDOS X, IBM/Toshiba 4690 OS, PTS-DOS, SISNE plus, and in the DEC RT-11 operating system.

RSTS/E

RSTSRSTS-11
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 system) of the RSTS/E timesharing system or under RTEM (RT Emulator) on various releases of both RSX-11 and VMS.
The RSTS kernel could now be compiled under the RT-11 RTS, formatted as a kernel file with RT-11 SILUS, and copied to the system or other disks, while the computer was time-sharing.

Peripheral Interchange Program

PIP
The utilities DIR, DUP, PIP and FORMAT allowed a user to manage their disk volumes.

TSX-Plus

TSX
S&H Computing developed and distributed TSX-Plus, a multi-user, multi-processing implementation of RT-11.
It was developed by S&H Computer Systems, Inc. and is based on DEC's RT-11 single-user real-time operating system (TSX-Plus installs on top of RT-11).

DECnet

File Access ListenerCCNETDIGITAL Network Architecture
It is even possible to network RT-11 machines using DECNET, the Internet and protocols developed by other, third-party sources.
The initial implementations released were for VMS and RSX-11, later this expanded to virtually every operating system DIGITAL ever shipped with the notable exception of RT-11.

DIGITAL Command Language

DCL.DCLDCL command prompt
The implementation of DCL for RT-11 increased its compatibility with the other DEC operating systems.
DCL had its roots in the IAS, TOPS-20, and RT-11 OSs and was implemented as a standard across most of Digital's OSs, notably RSX-11, but took its most powerful form in the OpenVMS OS.

Electronika BK

Elektronika BKBK-0010Elektronika BK-0010
One of the operating systems was ANDOS, although officially the computer was shipped with OS BK-11, a modification of RT-11.

FOCAL (programming language)

FOCALFOCAL-69FOCAL Mod V
When ported to the PDP-11, the resulting FOCAL-11 relied on the underlying operating system, RT-11, to provide file support and editing.

DECtape

LINCtapeDECtape IIcartridge tape
Distributions were available pre-installed or on punched tape, magnetic tape, cartridge tape, or floppy disk.
The RT11 single-user operating system can be bootstrapped from a TU58, but the relatively slow access time of the tape drive makes use of the system challenging to an impatient user.