The Untold Unix Story

This is an "untold" story in UNIX which had a major effect on the current environment of UNIX-like operating systems such as the BSD's, Minux and Linux. I wonder where we would be today without the seminal work of people like John Lions who took the time to go through the UNIX System 6 source code and document what each piece of the puzzle did, so it could be taught to those of us interested in learning more about the workings of the system. The paper John wrote went viral and even was published as a book. Force to remove it from publication in 1979 it returned finally in 1996 and is still available today. "You are not expected to understand this" became the hallmark quote of this early work.

00:00 - Intro
00:48 - Quote
01:40 - OS Approach 1
02:40 - OS Approach 2
03:28 - OS Approach 3
04:29 - UNIX is released
05:52 - 1975 Unix System 6 Release
07:21 - Commentary on UNIX
08:24 - John Lions Quote
09:34 - The Book
10:21 - System 7
12:13 - Minix
12:57 - Linux
13:29 - Re-Release of John Lions Book
15:11 - NextGen OS
16:03 - Tagline
20:21 - Outro

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[FarrellMcGovern]

Thank you for this video. I have been working on Unix flavoured operating systems for 30+ years, starting with SunOS/Solaris, then getting into Minix and finally Linux, as well as dipping my toes into a number of flavours of Unix along the way. I never had the money, or the grades (due to dyslexia & dyscalculia) to get into University, but I bought Tannenbaum's "Operating Systems: Design and Implementation" when it came out and started fiddling with Minix. This is where most of my initial knowledge of Unix and Linux came from. When Linus came out with his kernel, as soon as there was a boot and root disk available, I downloaded them and would go around at work when people were not using their 386 systems and boot up Linux to poke around with it. Back then, access to Usenet was one of my primary sources of information, and it's importance in helping to build our current computer world, I think, has been forgotten.

[StephenFrede]

John Lions was a professor at the University of New South Wales, in Sydney Australia - not South Wales in the UK. I completed his Operating Systems course in 1981 as part of my Computer Science degree and both the Unix V6 source code as well as John Lions' commentary were required textbooks. I still have my copies, with the source code signed by Dennis Ritchie and the commentary signed by John. Attending his funeral a few years later was a sad day for everyone who knew him as well as the community at large.
The source code is a great teaching resource, including a privilege escalation vulnerability in a system call, discovered (and exploited) by someone in my honours class at uni.

[FrancoCatrin]

Thanks for doing these videos! I'm not so young but you make me feel like hearing grandpa's great stories about how we get here as society, full of interesting details! Thanks again!

[larryciesla]

Wow!. At 73, I lived through all this at Western Electric and Bell Labs. What a trip down memory lane! Guys like Ritchie and others involved in the development of Unix were legends in the company. I personally learned a tremendous amount by studying the Unix OS code. The most valuable lesson: How not to write comments in the code - as the very sparse and cryptic comments taught so well! Thank you for this most excellent presentation.

[jecelassumpcaojr]

A detail about the "you are not expected to understand" code is that originally C used "x =+ 8" as the shortcut for "x = x + 8", but that proved to be too ambiguous as "x = +8" meant assign positive 8 to x. So they switched to "x += 8" to eliminate any possible confusion. The code shown is "rp->p_flag =& ~SSWAP;" would be written as "rp->p_flag &= ~SSWAP;" in more modern C, meaning: clear the SSWAP flag pointed to by rp.

[corvoattano]

Mister, you are one of the best content creator I’ve seen. You are able to retain audience attention with just story telling, presented in a gracious and coloquial manner, no matter how arid the subject is. Kudos, sir.

[rfvtgbzhn]

15:54 an NT-based version of Windows. Windows NT was based on OS/2 1.3 and the development of OS/2 started in 1985, so I guess the baseline is from 1985. The baseline of Linux is actually newer, it's really from 1991. It is intended to be compatible with Unix, but doesn't contain any Unix code for copyright reasons.

[hellNo]

as a youngster in the field, I really appreciate you sharing this info with us in a really well formatted and paced way. understanding the behind the scenes feels as important because we can learn to avoid mistakes that happened with licencing and distribution and long term development of such a big project as an OS. Great video thank you for sharing!!!

[ropersonline]

12:53: Minix is also hard to escape in current year, because it's in almost every major Intel CPU/chipset.
Per Wikipedia: "Intel chipsets post-2015 are running MINIX 3 internally as the software component of the Intel Management Engine."

[OpenSourceAnarchist]

Absolutely love video essays like this. What a wonderful story that had a wonderful impact all these years later. Glad it's not lost to obscurity in time!

[ericanderson]

I can't thank my college enough (and AT&T) for the opportunity to work with and make changes and improvements to the UNIX system in the late 1970s, that was used for student computing. Having the free source code to examine, edit, and build was a great basis for my career.

[Kamel]

Thank you for making this video, it's such a treasure to me.

As a long time Linux and open source enthusiast, I have had such a hard time getting people to understand and appreciate this origin story. The fact that Bell Labs retroactively revoked the ability to use the source is why the GPL is the way it is (and why GNU means "GNU is Not Unix"). That along with Xerox distributing only precompiled binaries (previous to that, it was typical for companies to distribute software + source code and Stallman had custom modifications).

From wikipedia:
> In 1980, Stallman and some other hackers at the AI Lab were refused access to the source code for the software of a newly installed laser printer, the Xerox 9700. Stallman had modified the software for the Lab's previous laser printer (the XGP, Xerographic Printer), so it electronically messaged a user when the person's job was printed, and would message all logged-in users waiting for print jobs if the printer was jammed. Not being able to add these features to the new printer was a major inconvenience, as the printer was on a different floor from most of the users. This experience convinced Stallman of people's need to be able to freely modify the software they use.

These things compelled a lot of smart and passionate people to find a solution, and many of them were doing things in isolation (Minix, GPL, Linux, BSD) as disparate bespoke systems until the world began ultimately to see them as part of a larger single movement.

This is really important to understand, because people have a really hard time understanding why once something is open source you can't close it again - that's the very behavior they set out to prevent with GPL. Finally, I'll add that this story highlights the clear and apparent friction that took place as a result.

[CyberGizmo]

Explanations: First, I said the Academic version of UNIX was free, this was true later, but they had to pay $150 for an administrative fee.

[wissemyahiaoui]

As computer engineer and Linux/Unix enthusiast, I am happy to find such channel with a wonderful creator
Dankeschön

[andrewjackson]

I am thankful for the history. I'm just a little younger than you but didn't become a developer. I stayed on the systems consultanting and implementation side. I remember playing with BeOS on my PII 266 MHz and was amazed at the speed. It got me looking into other OSs besides Windows. I fell I love with NetWare. But some Unix history is still beyond my years so I love to understand the roots. Cheers.

[dipi]

On my 14 years old main rig, I just compiled two versions of my custom Linux kernel, derived from Linux 6.0.6, slightly patched, one optimized for speed, one for size.
Both custom kernels were compiled in just over 2 minutes each. Both kernels boot my trusty old rig in unter a second (<1s) from GRUB2 to KDE + networking.
Only Linux and free software make me feel in control to such a geat extent.
Result: ease of mind.
Cheers!

[GaryL]

The breakup of the Bell System was indeed a two-edged sword. The Labs were a unique resource, non-governmental with all of that baggage and non-commercial with the shortsightedness of commerce. One of the worst results of the use of Antitrust.

[sysadmin]

Please keep putting out videos. You're content is invaluable.

[eyesonly]

I came through my undergrad CS years just after UNIX had been locked down. So we had no coursework level access to it. However, I had a few friends that were doing their Masters at the time, and they had managed to load a bootleg copy of UNIX onto a PDP-11 they had in the graduate lab. Interesting stuff at the time.

[KAZVorpal]

I was using Linux in 1992, and it was effectively open source.
I don't know if it used some specific licensing scheme, maybe that came later, but the way we set up Linux was to download the dozen or so images off Usenet, write them to floppies with rawwrite, install them to a hard drive, and then edit and compile the kernel's source ourselves. It was open source in every practical sense.