“Mainframes were not a special issue for OS/2, “
Not true, some technical issues but many more politically. I have had a lot of direct experience with IBM field reps poo-poo-ing OS/2. We needed a small database server at a large bank and the entire IBM team and some sent in from HQ dissuaded us. We got a Sun. Ran ORCL which actually had much better DB2/DB2 integration!!! Worked great. This was ORCL 6.32 the most solid ORCL ever.
This was part of IBM’s attempt to moat CICS and kill C/S computing.
That’s anecdotal...besides, all new systems have *some* issues at integration. And all new systems will have a few places where they either can’t be made to work, or will create an obvious opportunity for a good competitor to step in and fix it with their stuff.
All I am saying is that mainframe integration was absolutely *not* the core problem that doomed OS/2. They had Communication Manager/2 (a high performance SNA stack) and DB2/2 (a horribly named OS/2 version of DB2) and a “host” (hahaha) of other mainframe era apps ported to OS/2 and keeping a high percentage of their big iron customers (like Ford, Fireman’s Fund, and others) happy from the beginning.
What doomed OS/2 was the absolutely retarded decision to design it for the 286 processor using the 286’s “protected mode” for OS/2 and then resetting the processor into real mode on the fly to run legacy programs in the single “Dos box.”
Then what followed during the divorce from Microsoft were a cascade of retarded decisions made by really bad IBM management.