DEC RSX-11D and its COBOL compiler?

Paul Koning paulkoning at
Tue May 29 08:46:43 CDT 2018

> On May 29, 2018, at 9:38 AM, Guy N. via cctalk <cctalk at> wrote:
> On Tue, 2018-05-29 at 17:30 +1000, Nigel Williams via cctalk wrote:
>> On Tue, May 29, 2018 at 1:27 AM, Al Kossow via cctalk
>> <cctalk at> wrote:
>>> I have 11D on bitsavers.
>> this is actually RSX-11D?
> As I recall, IAS ("Interactive Applications System") was a timesharing
> environment layered on top of RSX-11D.
> When I was working with RSX-11D many years ago, I heard the opinion
> expressed (maybe by DEC field service?) that RSX-11D was a pig, and IAS
> was an elephant on a pig's back.

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.  


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