Sure, but then DEC Field Circus won't touch the box.
That's not true. All our UNIX systems at UCB and CMU had DEC field service on them and we had lots of non-DEC HW, including memory, disk and disk controllers. Funny, the DEC knew we could swap memory chips on the National Semiconductor memory board for the Vax. Which we could not do with the DEC boards, they had to be swapped.
The same was true at BTL, in fact and at Bell, there were DEC folks on-site. They might occasionally gripe, but we used to joke about it. It probably helped in all these places we had more than multiple systems and the field offices knew better. If we called, it was busted.
Heh heh :-) I don't think I've ever seen RS-232 used "properly" i.e.
implementing DSR/DTR or RTS/CTS for other than flow control etc, and using
the secondary pins as well.
Maybe you never saw a serial RJE station or I suspect a serial line that was fully synchronous running one of the IBM protocols. That was sort of where I started to learn in the late 1960s. I saw IBM systems before I saw the DEC ones and IBM used all the wires. Eventually, I got a copy of the wonderful DEC press book from John McNamara, called "Technical Aspects of Data Communications."
Then I learned about UNIX, which came from AT&T which used all that stuff in their modems and data communications gear.