RSX-11
INTRODUCTIONRSX-11 is a family of real-time operating systems for PDP-11 computers, created by Digital Equipment Corporation (DEC); it was common in the late 1970s and early 1980s. It was designed for and much used in process control, but was also popular for program development.
RSX-11 began as a port to the PDP-11 architecture of the earlier RSX-15 operating system for the PDP-15 minicomputer, first released in 1971. The main architect for RSX-15 (later renamed XVM/RSX) was Dennis “Dan” Brevik.
Principles first tried in RSX-11M later appeared in DEC's VMS. Microsoft's Windows NT system is a distant descendant of RSX-11M but is more directly descended from an object-oriented operating system Cutler developed for a RISC processor (PRISM) which was never released. This lineage is made clear in Cutler's foreword to Inside Windows NT *click here*, quoted on Neil Rieck's "Windows-NT" is "VMS re-implemented" page.
An excellent review of the RSX-11 Operating System can be found in the RSX-11 Technical Summary *click here*. I would suggest that as a great starting point for anyone interested in RSX.
RSX-11 VERSIONS
- RSX-11A,C - a small paper tape real time executives.
- RSX-11B - a small real time executive based on RSX-11C with support for disk I/O. To start up the system, first DOS-11 was booted, and then RSX-11B was started. RSX-11B programs used DOS-11 macros to perform disk I/O.
- RSX-11D - a multi-user disk-based system. Evolved into IAS; a timesharing-oriented variant of RSX-11D released at about the same time as the PDP-11/70. The first version of RSX to include DCL (Digital Command Language), which in IAS is known by its original name, PDS (Program Development System).
- IAS - a time-sharing-oriented variant of RSX-11D released at about the same time as the PDP-11/70. The first version of RSX to include DCL (Digital Command Language), which was originally known as PDS (Program Development System).
- RSX-11M - a multi-user version that was an adaptation of the earlier RSX-11D for a smaller memory footprint, it was popular on all PDP-11s; Dave Cutler was the project leader.
- RSX-11S - a memory-resident version of RSX-11M used in embedded real-time applications. RSX-11S is a dedicated, execute-only system. Using the sophisticated development tools on an RSX-11M, RSX-11M-PLUS, or VAX/VMS system, programmers can develop, test, and debug applications and then download them to an RSX-11S system.
- RSX-11M-Plus - a much extended version of RSX-11M, originally designed to support
the multi-processor PDP-11/74, a computer that was never released, but also used widely as a
standard operating system on the PDP-11/70.
RSX-11M-Plus also ran on PDP-11/44, PDP-11/84, PDP-11/94 (Unibus machines), as well as PDP-11/73, PDP-11/83,
and PDP-11/93 (QBus machines).
One of the advantages of RSX-11M-Plus over RSX-11M was that larger programs could be created. This was achieved by having the task builder (the linker) build the program to use the separate instruction and data space feature of some PDP-11 models to put executable code and data into separate address spaces. This also allowed programs to run faster, as it reduced the need for "overlays", in which you could overlay object modules at task build time, for very large programs. Overlays were specified in a task build command file.
- RSX-20F - PDP-11/40 front end processor operating system for the KL10 processor. Derived from RSX-11D and RSX-11M.
- Micro/RSX - a stripped-down version of RSX-11M-Plus implemented specifically for the Micro/PDP-11, a low-cost multi-user system in a box, featuring ease of installation, no system generation, and a special documentation set.
- P/OS - A version of RSX-11M-Plus that was targeted to DEC's PRO-325, PRO-350, and PRO-380 line of PDP-11-based personal computers.
- DOS/RV, OSRV-SM - Two names for the clandestine clone of RSX-11M that was produced in the Socialist bloc. This system appeared to be an exact duplicate of RSX-11M save that the prompt was changed in the binary files. According to other sources, RSX-11M source code might have been stolen by the KGB. If read as Cyrillic, the name OSRV is an abbreviation for 'Operatsionnaya Sistema Realnogo(Razdelenija) Vremeni'; Russian for 'Real Time(Time dividing) Operating System'. Not surprisingly, the six-character string 'OSRVSM' fits nicely in the same 16-bit RADIX-50 word as 'RSX11M'. But, there are differences between RSX and OSRV because of differences between SM and PDP's hardware and recognized by Soviet engineers bugs in RSX. (OSRVM is the next model of OSRV-SM for the -1425.) But RSX11M 'patched' for the SM's processor was used more often than rewritten OSRV. That happened because of better work by the RSX-11's re-coders, stability of patched RSX, and a faster update cycle for SM-RSX drivers and patches, made possible by the SM users community. OSRV and RSX driver interfaces are different and incompatible.
RSX first began as a small paper tape based real-time executives (RSX-11A, RSX-11C) which later gained limited support for disks (RSX-11B). 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. 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 to 1976, the RSX-11M project was spearheaded by noted operating system designer Dave Cutler, then at his first project. Principles first tried in RSX-11M appear also in later designs led by Cutler, DEC's VMS and MICA and Microsoft's Windows NT.
Under the direction of 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. 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) 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, in Digital's UK facilities.
LEGAL OWNERSHIP TODAY
RSX-11 is proprietary software. Copyright is asserted in binary files, source code and documentation alike. It was entirely developed internally by DEC. Therefore, no part of it is 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 auto-configuring 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 Inc. in March 1994 as part of a broader agreement. Mentec Inc. was the US subsidiary of 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. The PDP-11 software, which was owned by Mentec Inc. was then bought by XX2247 LLC, which is the owner of the software today. 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.
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 and then to Hewlett-Packard in 2002. In late 2015 Hewlett-Packard split into two separate companies (HP Inc. and Hewlett Packard Enterprise). It's uncertain which company holds the rights to RSX and IAS. No new commercial licenses have been issued since at least October 1979 (RSX-11A, RSX-11B, RSX-11C) or 1990 (IAS), and none of these operating systems were ever licensed for hobbyist use.
Guides
Sources:
- Adapted from: Gunkies.org, RSX-11.
- Adapted from: Wikipedia DEC RSX-11.
- Source: RSX image creation for PiDP-11 (emulator) using RSX-11M-PLUS V4.6.
- Source: PDP-11 Hardware; Github. Good source for setting up a SIMH Raspberry Pi (PiDP-11) with an RSX-11 OS.
- Source: Crouze.com, running a web server on a PiDP-11/70 with RSX-11.
- Source: Russian website with links to various PDP-11 SIMH sites and utilities. Good starting point for software.
- Source: Obsolescence Guaranteed. Web site for sourcing and using a PiDP-11. Good site for reading up on PiDP11s
- Source: BQTCP/IP - A TCP/IP implementation for RSX; author Johnny Billquist.
- Source: Hackaday.IO - Building a PiDP-11. How it's done and how to order one by the original creator of the PiDP-11/70.
Compiled on 08-30-2024 10:36:39