MINIX's creator would have liked to have known Intel was using it

Few people knew MINIX was running in most Intel processors, including its creator.
Written by Steven Vaughan-Nichols, Senior Contributing Editor

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When Andrew S. Tanenbaum created the educational, open-source operating system MINIX, he did it to teach operating system principles to his students at Amsterdam's Vrije Universiteit and to readers of his classic textbook, Operating Systems Design and Implementation. MINIX would become Linux's forefather. Tanenbaum knew that. What Tanenbaum didn't know was Intel would take MINIX and embed it within its CPUs for almost a decade.

As Tanenbaum wrote in an open letter: "Thanks for putting a version of MINIX inside the ME-11 management engine chip used on almost all recent desktop and laptop computers in the world. I guess that makes MINIX the most widely used computer operating system in the world, even more than Windows, Linux, or MacOS. And I didn't even know until I read a press report about it."

Now, Intel was within its rights to do that. MINIX has been licensed under the BSD license since April 2000. The only thing this license requires of its users is they include the original copyright notice. Other than that, you can do what you want with it.

Tanenbaum had hoped, as late as 2011, that this would lead to commercial success for MINIX. In an interview, he said, "Now as we are starting to go commercial, we are realizing the value of the BSD license. Many companies refuse to make major investments in modifying Linux to suit their needs if they have to give the code to their competitors. We think that the BSD license alone will be a great help to us."

It didn't work out that way.

Intel had approached Tanenbaum about using MINIX. In his open letter, he revealed, he "knew that Intel had some potential interest in MINIX several years ago when one of your engineering teams contacted me about some secret internal project and asked a large number of technical questions about MINIX, which I was happy to answer. I got another clue when your engineers began asking me to make a number of changes to MINIX."

Then, Tanenbaum continued, "There was radio silence for a couple of years, until I read in the media that a modified version of MINIX was running on most x86 computers, deep inside one of the Intel chips. This was a complete surprise. I don't mind, of course, and was not expecting any kind of payment since that is not required."

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Still, he would have appreciated being told. It "would have been nice is that after the project had been finished and the chip deployed, that someone from Intel would have told me, just as a courtesy, that MINIX was now probably the most widely used operating system in the world on x86 computers," he said.

Ironically, in an IEEE Computer interview, Tanenbaum revealed an early Intel chip program led in part to the creation of MINX. He had started work on MINIX when AT&T closed the source for Unix Version 7 in 1979. This made it impossible to study the operating system deeply. Tanenbaum called this "the dumbest mistake in all of history."

Tanenbaum started working on developing a Unix Version 7 compatible operating system, but it kept crashing. Then, one of his students told him it was happening because the Intel chip was overheating and causing an interrupt 15.

This ticked-off Tanenbaum: "I said all these very unpleasant things which I cannot repeat about Intel. If they want to put a thermal sensor [in their chip] great please put it in the manual." Armed with this knowledge, he was able to get MINIX working.

If his student "hadn't made that comment, there would have been no MINIX," he said. "If there were no MINIX there'd be no Linux because Linus went out and bought a PC specifically for the purpose of running MINIX. If there had been no Linux, there would have been no Android."

So, perhaps Intel should, you know, at least acknowledge his contribution to not just its chips, but also its entire business model. Without MINIX, we'd be living in an entirely different technological world.

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