I think the Burroughs machines also had a stack-based architecture

https://www.hoa.org/blog/jack-allweiss/evolution-of-burrough...

I had to use a Burroughs mainframe for development during the first year of my CS course in 1983 - might have been interesting hardware but the user experience was ghastly - some awful thing called CANDE = although I did get a laugh out of all of the references to the MCP.

In retrospect I do wonder if they did that so that when we moved to Unix machines later in the course we'd really appreciate them!

	▲	satiated_grue 3 days ago \| parent [-]
		MCP is still available from Unisys, which was formed by the "merger" of Burroughs and Sperry Univac. It was first released in 1961 - is there any other software, particularly an OS, still in production after that long? https://en.wikipedia.org/wiki/Burroughs_MCP