No, I'm talking in general "computer companies" from that era that dominated. Many of those were mainframe-type companies. I'm not sure who Tandem's competitor was, but from googling, the name Stratus did come up. I don't remember that name. From looking further, it's amazing how many of these companies were gobbled up by HP in one way or another.
Yes, Stratus sounds right. HP bought plenty of hardware companies, but will have to think if they spent much buying software companies.