Video summary

The most used operating system in the world is not Linux

Main summary

Key takeaways

Educational

Main ideas & lessons

  • The “most used operating system” isn’t what most people think.

    • The video argues that on Intel x86 PCs, a form of MINIX is used behind the scenes inside the Intel Management Engine (ME)—often without users knowing.

  • A long chain of historical irony:

    • MINIX was created to enable teaching operating-system internals after UNIX licensing restrictions made studying UNIX source code in courses illegal.
    • Linux emerged partly because its creator Linus Torvalds encountered MINIX’s limitations and built a kernel instead.
    • The key “fork” is licensing, not technical design: the differing licenses (BSD vs GPL/copyleft) shaped how each system was later used.

  • Technical point used to support the claim:

    • A Google engineer (Ronald Minnich) reports reverse engineering that the Intel Management Engine runs a modified, closed MINIX 3.
    • The ME is described as:
      • small
      • isolated
      • modular
      • running at a privilege level “ring minus three” (below what the OS kernel can reach)
      • operating largely independently of the main OS

Concepts and chronology (structured)

  1. UNIX licensing change creates a teaching crisis

    • Before the 1970s: UNIX source code was used in universities because it was readable and studied.
    • Then AT&T changed the UNIX license (after UNIX v7) to forbid studying the source code in courses.
    • Result: professors had to teach OS internals via theory or fake systems.

  2. MINIX is created as a workaround for classroom constraints

    • Andrew Tanenbaum (professor in Amsterdam) responds by rewriting an OS for teaching:
      • From scratch
      • Compatible with UNIX for users
      • Not copying AT&T UNIX code
    • MINIX’s design emphasizes:
      • small codebase (about 12,000 lines, intended to be readable within a semester)
      • educational simplicity
      • a culture of keeping it small (refusing growth/extra features)

  3. Linus Torvalds builds Linux partly because MINIX was too limiting

    • A Finnish student, Linus Torvalds, gets a 386 and becomes frustrated with MINIX’s limits.
    • In 1991 he writes his own kernel:
      • Initially named Freax (“free/freak/unix” blend)
      • University admin Ari Lemke changes it to Linux without asking.

  4. The “real” pivotal factor: the license fork

    • Early versions: Linux was tied closely to MINIX (even running on the MINIX filesystem at first).
    • Then license divergence:
      • Tanenbaum (MINIX): later releases MINIX 3 under BSD (permissive: can be used/sold/closed as long as attribution/name is kept).
      • Torvalds (Linux): places Linux under GPL (copyleft: if redistributed with modifications, source must be shared).
    • Video’s thesis: BSD permissiveness enabled Intel to use MINIX in a closed way, while GPL would have forced openness.

  5. MINIX matures and gains a self-healing feature

    • In 2005, MINIX 3 is released as a serious system.
    • The video highlights a component called the “reincarnation server”:
      • monitors parts of the system
      • kills/restarts crashed or stuck components without rebooting the whole machine
      • described as avoiding failures like Windows blue screens or Linux freezes
    • Emphasis repeated: the design is small, isolated, repairable.

  6. Reverse engineering allegedly identifies MINIX inside Intel chips

    • In 2017, at a conference, Ronald Minnich reports:
      • Intel’s Management Engine is a hidden, independent processor subsystem.
      • It has deep access: machine, network, memory, everything.
      • The OS inside it is identified as a modified, closed MINIX 3.

  7. Tanenbaum learns after the fact and writes an open letter

    • Intel previously contacts him and asks questions to shrink MINIX further.
    • After years, he reads the news that MINIX runs inside Intel chips.
    • He writes an open letter to Intel leadership:
      • tone described as wounded politeness
      • he thanks them but notes he wasn’t told as a courtesy.

  8. Final lesson: licenses determine whether code becomes transparent or a sealed black box

    • Video’s argument contrasts outcomes:
      • BSD allowed MINIX to be modified, closed, and embedded invisibly.
      • With GPL/copyleft, Intel would likely have had to publish modified code.
    • Video claims: freedom is protected not by “best code,” but by the “right license.”

Methodology / instructions presented (if any)

  • No step-by-step “how-to” method for viewers is provided.
  • The closest “instruction-like” structure is a repeated conceptual checklist:
    • Remember these recurring design qualities: small, isolated, repairable
    • Remember the “fork” decision points:
      • BSD vs GPL
      • how each affects whether modifications must be released when redistributed

Speakers / sources featured (as named in the subtitles)

  • Andrew Tanenbaum
  • Linus Torvalds
  • Ari Lemke (university administrator who renamed “Freax” to “Linux”)
  • Ronald Minnich (Google engineer; reported reverse engineering of Intel Management Engine)
  • Intel (as an organization; referenced as the party embedding MINIX in chips)
  • AT&T (as the company that changed the UNIX license)
  • The video narrator / author (unnamed; provides commentary and interpretations)

Original video