[acqq]

> Unix (...) first source license was sold in 1975.

> VMS was released in 1977 as VAX/VMS on the VAX series of computers. Before VMS the DEC hardware ran various other operating systems such as RTX-11, TOPS-10, and optionally AT&T Unix

Before VMS there was RSX-11 (note RSX not RTX):

https://en.wikipedia.org/wiki/RSX-11

"From 1971[5] to 1976 the RSX-11M project was spearheaded by noted operating system designer Dave Cutler, then at his first project.[5] Principles first tried in RSX-11M appear also in later designs led by Cutler, DEC's VMS and Microsoft's Windows NT.[6][7][8]"

In Dave's words:

https://tech-insider.org/windows/research/1992/11.html

"RSX-11M was introduced in 1973, 18 months after we started building"

Note Dave Cutler and note the years. I'd say the history is comparable.

[cestith]

Thanks for pointing out the typo. I'll fix that.

Note "heavily influenced" doesn't make RSX-11 any more VMS than it makes Multics into Unix, or CP/M into MS-DOS, or the NeXT into a Mac, or an Alto into a Mac or Windows.

Also note that 1973 doesn't significantly predate 1973. Don't confuse the first source license same with the announcement of availability, which I also noted. And Unix was in use internally at AT&T the same year DEC started on RSX-11.

[acqq]

Dave Cutler was the developer of of RSX-11, VMS and the NT.

I don't claim that his entire life work predates the work of somebody else, just that the products he delivered are definitely comparable in its commercial availability with Unix.

I would also be not surprised if his products had more users at these first years than Unix did. To do the history right one should not project the results visible today (or which happened much later) to the history.

[cestith]

The claim I was correcting was that VMS itself predated Unix itself. This claim is false on its face. Yes, multiple people in the history of the field have worked on more than line project.