IAS is basically RSX-11/D under the covers, with some minor tweaks and with a sort of timesharing added. If I remember right that involved a new type of partition where memory was managed more dynamically. I worked on Typeset-11 which was written for RSX-11/D and then ported to IAS, where the timesharing part was left out since we had no use for it. So the "port" didn't involve any real change, not even for drivers. At one point DEC pushed to retire RSTS/E and replace it with IAS; that notion was a miserable failure because IAS timesharing wasn't nearly as good. paul

Sounds right to me. RSX-11/D could fit in 124 kwords, but not all that comfortably. IAS required 22 bit addressing. RSX-11/M was apparently created in response to that piggishness. I once saw an RSX-15 kernel listing, which had a lot of very familiar looking data structures -- it implied that RSX-11/D had its origins, at least as far as overall design is concerned, in RSX-15. paul

No. IAS (not AIS) is an RSX-11/D variant that intended to add timesharing capabities to RSX-11/D. RSX-11/D was pretty much limited to fixed purpose real-time and turnkey applications (such as Typeset-11) because of the inflexible way in which it managed memory through "partitions". That term also shows up in RSX-11/M, I think, but in /D it was quite rigid and not suitable for situations where the applications to be run were not known ahead of time -- as would happen in timesharing systems with programmers using it. paul

Yes. The two V3.4A tapes will allow you to build either RSX-11D or IAS. I believe that this was the last supported release. John.

My first job in Maynard was project lead for DECnet-11D & DECnet-IAS (Phase II). It was basically the same source code for both, just separate builds since they were released as separate distributions. Later versions consolidated the releases into a single kit. The V3.4A tapes will claim to be running IAS but, if you select the ?Real-Time? options during sysgen you?ll get the familiar MCR> prompt: 1920K (word) IAS Version 3.4A Baselevel 3414 SAV -- Partition GEN expanded by 57472 words MOUNT-**Volume Information** Device =DB0 Class =File 11 Label =IASSYS UIC =[1,1] Access =[RWED,RWED,RWED,RWED] Charac =[] MOUNT -- DB0 ** Mount Complete ** 20-NOV-90 12:15:53 Date and time, please? MCR> IIRC, IAS development in Reading was done mostly on an 11/45. The 2.0 SPD confirms that IAS was supported on 11/45, 55 and 60 but only with 2 active terminals. John.

On 05/30/2018 10:33 AM, John Forecast via cctalk wrote: I find this conversation very interesting.? I was always led to believe that when Mentec got all the PDP-11 OSes except IAS? (supposedly because DEC still had government commitments) that it eventually faded into obscurity and was lost. Obviously, not the case.? Has anyone ever approached HP about the possibility of just releasing it all to the world as either Licensed Open Source or just public domain?? Not my favorite OS by any means, but better than the nothing we have for the PDP-11 today. bill