Home > RSX-11

It existed in many versions:

• RSX-11/A, C -- small paper tape real time executives.
• RSX-11/B -- small real time executive based on RSX-11/C with support for disk I/O. To start up the system, first DEC DOS was booted, and then RSX-11/B was started by some command that I do not recall. RSX-11/B programs used DEC DOS macros to perform disk I/O.
• RSX-11/D -- evolved into IAS
• RSX-11M -- a multiuser version that was popular on all PDP-11s.
• 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. The first version of RSX to include DCL ( Digital Command Language).
• RSX-11S -- a memory-resident version used in real-time applications.
• RSX-20F --11/40 front end processsor operating system for the DEC KL10 processor. Derived from RSX-11S
• Micro/RSX -- a stripped-down version 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.

more directly descended from an object-oriented operating system Cutler developed for a RISC processor which was never released. This lineage is made clear in Cutler's foreword to Inside Windows NT, quoted on Neil Rieck's "Windows-NT" is "VMS re-implemented" page.

1 Quotation

• "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.

• "My first operating system project was to build a real-time system called RSX-11M that ran on Digital's PDP-11 16-bit series of minicomputers. ... a multitasking operating system that would run in 32 KB of memory with a hierarchical file system, application swapping, real-time scheduling, and a set of development utilities. The operating system and utilities were to run on the entire line of PDP-11 platforms, from the very small systems up through the PDP-11/70 which had memory-mapping hardware and supported up to 4 MB of memory." -- David Cutler, foreword to Inside Windows NT

2 External links

• Dan Brevik posted a history of precursors to RSX-11 in alt.sys.pdp11.

• Dan's RSX-11 prehistory contain documents which trace RSX-11 back through RSX-15 and the real time executive written by John Neblett in the late 50's for the RW-300 process control computer.

• Al Kossow posted some further notes on RSX-11 in alt.sys.pdp11.