I was born a decade or two too late to really experience mainframe computing. I briefly did some IBM 3090 and System 390 stuff, and Tandem if that counts.

However, I'm more curious about the competing mainframes from the Seven Dwarves or BUNCH.

Specifically, I'd like to understand more about:

Burrough's MCP
Univac's EXEC (now OS2200)
Control Data's NOS/VRE
RCA Spectra's VMOS

I found that Unisys provides desktop (Windows) emulation environments for modem versions of MCP and OS2200.

I've also found the Desktop Cyber emulator for Control Data.

I haven't seen anything out there on the NCR or RCA machines.

I've also left off the GE > Honeywell > Bull GCOS operating system for no good reason. It just doesn't interest me that much.

Does anyone have any interesting comments that contrast these different environments?

Or, should I just recognize that these things get the market share that they deserve, and just spend more time with DEC / Unix OSs ?