DEC RSX-11D and its COBOL compiler?

John Wallace johnwallace4 at
Tue May 29 14:39:47 CDT 2018

[apologies for lack of context, been away from cctalk a long time and insufficient recall of how this cctalk thing works... yet somehow still remember IAS on an 11/70 from the 1980s]

Pick an RSX layered product and lots of fundamental stuff would probably be compatible between 11M, 11D, and IAS (and/or 11M+). Find the RSX version and see if IAS is mentioned as supported in the SPD or other documentation. It often was, and even if it wasn't, lots of non-priv stuff would just work.

More IAS background from someone (not me) who was there in the IAS development team in DEC Reading:

"This page is dedicated to the best of the many PDP-11 operating systems - IAS

I couldn't find anything else on the Web about IAS… but it deserves better than to fall completely into obscurity.

DEC's approach to operating systems for the PDP-11 was anything but disciplined. New ones got invented every time some engineer or marketing person blinked. In the early days, there was a real-time kernel called RSX-11A, designed for memory-resident applications in what we now call embedded processors. Features got added to this rapidly - code bloat is nothing new. By the time it got to RSX-11D it had a complete disk-based file system, a program development environment, and support for every peripheral in the Small Computer Handbook (and there were plenty of them - peripherals on the PDP-11 obeyed the same strategic imperatives as operating systems - see above). At this time, a bright young engineer called Dave Cutler decided that enough was enough, and set out to create a small system that would do the same, which he called RSX-11M. We all know what happened to him - and he no longer even has the excuse of youthful excess.



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