I guess money, if you look at the history of computers the majority of interesting stuff failed because it didn't managed to pay for the investments that were done.
C and UNIX got widely adopted, because AT&T wasn't allowed to sell it, so they gave the source code for free to universities. Which then used the code to replace the expensive OSes that they were running on their mainframes.
When AT&T was allowed to charge for it afterwards, they tried to make people pay for it, but failed to do so.
Also around this time UNIX vendors started selling the developer tools separately instead of having them for free. This motivated many to contribute to GNU, which was largely ignored up to that point.
Sending you this link as you might have missed what actually happened on Burroughs end. I thought they petered out and got bought by Unisys. I didn't realize they were Unisys plus were selling billions in MCP systems.
That's probably true. Most material on the mainframe market says IBM has around 90% of it. Their revenues tend to suggest that, too. Probably the common effect with the First Mover advantage. I'm sure IBM bribing government officials in exchange for contracts helped, too. Let's not forget that angle. The NSA business alone would've been enough to found several, computer companies. ;)
"In September 1986 Unisys was formed through the merger of the mainframe corporations Sperry and Burroughs, with Burroughs buying Sperry for $4.8 billion. "
"The merger was the largest in the computer industry at the time and made Unisys the second largest computer company with annual revenue of $10.5 billion"
As to why IBM dominated, I have a hypothesis that's consistent with what happened to other companies. It's basically Gabriel's Worse is Better effect where certain characteristics improve marketing & uptake. The IBM mainframe, IIRC, were backward compatible or integrated with stuff IBM people already bought. They were optimized for Fortran etc that existing apps were written in where Burroughs was optimized for Algol, the language of the future. Further, in a trend that still exists, people focused on raw performance per dollar instead of reliability, maintenance, security, technical debt reduction, and so on that Burroughs architecture could provide. Similar effect with Intel i432, i960, and later Itanium w/ its excellent reliability/security improvements. Burroughs started taking out hardware security & recently got ported to Intel CPU's IIRC. Intel just stopped taking chances. Both in legacy mode since it's all people buy.
Sad story of how computer market works. The Burroughs systems are still around, though, with Unisys making plenty of money. MCP is on release 17 with Unisys also releasing a tool that lets you run MCP in a virtual machine on a PC. It's called MCPExpress I believe. Here's the page.
