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How “Master” and “Slave” Terminology is Being Reexamined in Electrical Engineering

October 06, 2020 by Tyler Charboneau

"Master” and “slave” have been used for decades in engineering vernacular. Now, many tech companies are pushing for more neutral terms.

The terms “master” and “slave” have drawn varying degrees of debate in engineering circles. And, in light of shifting norms and perceived racial connotations associated with the terms, many professionals are questioning their engineering necessity.

Accordingly, those in support of changing master-slave terminology argue that the terms' acceptance in the field speaks to the shortage of Black representation in the field. Only 3.53% of electrical engineering degrees were awarded to Black or African American students in 2017. 

What are the origins of this terminology in electrical engineering? And what are the stances in preserving or replacing these terms on an industry-wide scale?

 

The Meaning of Master and Slave in Electrical Engineering

“Master” and “slave” have been used for decades to describe the relationships between various components, process controls, and resource branches. “Master” may mean first, whereas “slave” accordingly is considered second.

 

Master and slave used on a circuit board

"Master" and "slave" used on a circuit board. Image used courtesy of VICE
 

These terms also have their places on the device side. Within a hardware ecosystem, a "master" device may serve as the hub while "slave" devices behave accordingly to its directives. 

Some practical examples: 

  • ATA hard drive groupings, where the "master drive" has communicative priority
  • "Master clocks" send timing signals to multiple “slave clocks" for synchronization

Both terms have traditionally described the hierarchical link between components and other technological elements. 

 

A Long-Held Discussion on Nomenclature Comes to a Head

2020 isn’t the first time that the nomenclature has been a talking point. In fact, as far back as 2003, Los Angeles officials suggested that manufacturers, suppliers, and contractors explore alternatives to master-slave terminology.

"Master" and "slave," despite their seemingly-innocuous meaning in computing, have inspired criticism for their perceived racial undertones. While minority professionals have led the charge to change the terminology, their requests haven’t been homogenous; white professionals and allies of the racial-equality movement have voiced their concerns as well.

 

Recently, EE Times contributor Leonard Ellis exhorted IEEE to retire the terms

Recently, EE Times contributor Leonard Ellis exhorted IEEE to retire the terms "master" and "slave," proposing "controller" and "responder" as an alternative. Image used courtesy of EE Times
 

That’s not to say that these terminology changes are universally praised. When an entire industry operates one way for a long time, those routines become entrenched and can be tangibly difficult to shift at a programming level. In Los Angeles’ case, vendors and manufacturers decried the proposal because it would require cumbersome relabeling and identification. 

Though the move was merely a suggestion, switching to new terminology does incur scaled costs—especially when a company must invest in their employees' efforts to make system-wide changes in terminology.

 

Tech Companies Changing the Terminology

Companies purporting themselves as culturally sensitive have pledged to consider employee complaints. At Twitter, a pair of engineers kickstarted the effort to change such terminology internally following months of lobbying—an effort that increasingly gained support at Twitter headquarters in tandem with the Black Lives Matter movement.

Here’s what Twitter Engineering had to say: 

 

Twitter Engineering's statement on inclusive language

Twitter Engineering's statement on inclusive language. Image courtesy of Twitter Engineering

 

The change was part of a greater campaign—its roots traced back to January—to replace many dubious terms throughout Twitter’s coding and documentation. The entire open-source community encompassing Twitter has faced these same challenges head-on. 

Perhaps no company is more synonymous with open source than GitHub—a preeminent development platform with over 40 million active users. The company has recently announced that it is converting any references to “master” with “main.” This is occurring within GitHub’s own repositories and documentation.

Immediate enforcement could impart plenty of instability upon existing repositories and projects. However, GitHub has promised a phased rollout. Individual developers are also encouraged to rename their own branches accordingly. GitHub is an indispensable tool for numerous tech companies. Consider that over 25,000 of Microsoft’s developers harness GitHub—underscoring the impact of one site's policy changes.

Additionally, Android, Go, the PHPUnit library, Curl have promised to take similar steps with related terminology. OpenZFS’ own adjustments have also emulated Twitter’s. Django and Drupal have also introduced alternatives to these terms.

 

A Question of Association

Some skeptics of the proposed master-slave terminology shift have acknowledged the inherently negative link between “slave” and “master” when used in tandem. However, many have expressed that while the former must be stricken from the EE vernacular, the latter term isn’t offensive in itself.

Python axed the terms "master" and "slave" from its programming language back in 2018, sparking the discussion of whether "master" can still be used so long as it is not in association with a "slave" counterpart. No need to alter both terms if the effort puts an undue burden on manufacturers and programmers, explained those opposed to the change.

 

GitHubs announcement to change master to main

GitHub's announcement to change "master" to "main." Image used courtesy of GitHub
 

As mentioned previously, GitHub made the shift from "master" to "main," even though a "slave" counterpart doesn't exist in GitHub's references. 

 

Alternatives to Master-Slave Terminology

Several companies have introduced their own approaches when nixing “master” and “slave.” Here are some proposed and instituted alternatives

  • Primary and secondary
  • Primary and replica
  • Primary and standby
  • Leader and follower
  • Conductor and follower
  • Source and sink
  • Main

 

A Change in Terminology May Require Steep Adjustments

For various reasons, the move to render “master” and “slave” technically obsolete has had its supporters and detractors. Supporters remark that Black engineers (and hopefuls) have already had to carve successful paths in a field that doesn’t represent them adequately. A change in this terminology would encourage more inclusivity in the field, they explain.

 

Race and ethnicity in electrical engineering by degrees awarded

Race and ethnicity in electrical engineering by degrees awarded. Image used courtesy of Data USA: Electrical Engineering
 

Detractors claim that the change is too expensive, time-consuming, or impactful upon existing systems. These individuals feel the adjustment period to new terminology would be too steep, should this change become ubiquitous, and the process of changing the terms may seem tedious at the onset.

Some vendors worry that companies may reject their products if changes don’t occur within certain time periods.

 


 

Editor's note: This article reports a general discussion on terminology occurring in the electrical engineering and tech communities at large. The comments in this article do not necessarily reflect the opinions of All About Circuits or All About Circuits site management.

26 Comments
  • P
    PhilTilson October 09, 2020

    I wondered how long it would be before this ridiculous nonsense hit the engineering community.  For heaven’s sake, these terms have been used and well-understood for years by people of every race and colour without hordes of disaffected minorities rushing to throw themselves under buses.  Let’s keep politics and political correctness out of engineering and stick to commonsense.

    Like. Reply
    • P
      pfabri October 09, 2020
      GitHub's move is particularly ridiculous. Like we've never heard of the term 'Master' anywhere outside the master-slave context e.g. a master-student, or a 'master record' in audio engineering. By the way: am I now a primary of electrical engineering or a conductor of electrical engineering? Where must I return my degree to have its wording changed? Even then, the change will probably be temporary: after all in a world where everyone is equal, a primary-secondary, or a conductor-follower relationship is also to be frowned upon...
      Like. Reply
      • G
        GT_1 October 09, 2020
        you hit the nail on the head....PC crowd will never be satisfied. It will continue to degenerate until it hits the bottom....whatever that is. some other examples that come to mind are "master plumber" or "master electrician"....how will the unions react to this? maybe call them "cuties"? good luck with that.
        Like. Reply
        • G
          GT_1 October 09, 2020
          and while we're at it, isn't that up arrow for VCC sexist?
          Like.
  • Sammy Iyi October 09, 2020

    THIS WILL NEVER STAND! This is utter B.S! These terminologies have been used for decades and has become part of all fields of Engineering. Whoever is having problems with the terms “master” and “slave” needs quick medical help! The circuits on which these terms are being used don’t give a hoot about these things! These terms has never and can never affect the operations of electrical/electronic circuits so why all stupid nonsense! Please the leaders of the Engineering community should focus on Engineering and keep politics out and VEHEMENTLY SHUN any form of SJW propaganda pushed their way. IT ADDS ABSOLUTELY NO VALUE TO THE ENGINEERING WORLD! except caos and confusion!

    Like. Reply
  • J
    JAB 1012 October 09, 2020

    The use of :- Main - Control 1 - Control 2 - Control 3 - etc, could be another way to label them.

    Like. Reply
    • P
      PhilTilson October 09, 2020
      But why??
      Like. Reply
    • G
      GT_1 October 09, 2020
      appease the authoritarians, let's hire a army of technical writers to make revisions of every piece of documentation in the last 50 yr. Oh, yeah, and the top required skill ---- be woke. Wait till you have to kiss their b---- every morning.
      Like. Reply
  • P
    paulosilveira October 09, 2020

    To be honest it is the first time I have heard someone relate slavery to racism. It never occurred to me.
    Slavery is the exploitation of a human being by another and in a broad sense it still exists.
    It is possible to find innumerable examples of slavery in mankind history in the last thousands of years, and in most cases it has nothing to do with racism, it is just the exploitation of the weakest by the strongest. Furthermore the slave trade in Africa had the collaboration of African born people.
    Recent episodes created a climate that is not helping, but to solve the problems that arose it necessary to prove that the color of the skin doesn’t matter, just the way people behaves matters. So it is useless to change the names master and slave, to controller and responder.
    The words master and slave have a well-known meaning and there is no reason to use another, because using them doesn’t mean that we approve slavery or that we are racists.

    Cheers,
    Paulo

    Like. Reply
  • grantday October 09, 2020

    I had absolutely no idea that there where only ever black slaves ... wow, consider me re-educated

    Like. Reply
    • K
      Kmpres October 11, 2020
      Look up the The Rise and Fall of the Holy Roman Empire and you'll get a good idea of what slavery is all about.
      Like. Reply
  • W
    wd73383 October 09, 2020

    Political correctness makes people dumb, and this article is a textbook example of that.

    Like. Reply
  • D
    danielZsocal October 09, 2020

    Nothing wrong with a commitment going forward to not use the terms Master & Slave.  As for historical use too much of a bother to try and change.

    Like. Reply
  • E
    EdwardP October 09, 2020

    Now that we’ve addressed the Master/Slave labels, we need to build on the momentum and fix the Male/Female connector issue.  However, if you can’t quite decide which connector type to choose, do not fret, you can plug in a gender changer and make the engineering change later.  Oh!, but that would need an engineering change order.  We can’t be allowed to order others to make changes.  Maybe we can modify the terminology to engineering change opinion.  But no! you never know what kind of opinion will be expressed, so the engineering change opinion has to pass through a fourth order filter and then get pushed through a hamming window to eliminate all sharp edges and spikey impulses it may contain. I’ll start working on the fourth order opinion filter.  I’ve been told mine needs to work better.

    Like. Reply
  • J
    JAB 1012 October 09, 2020

    By using:- Main - Control 1, Control 2, Control 3,—and so forth, that will end this that has harmed the world for decades.  MC-C1-C2-C3—- and so forth.

    Like. Reply
  • G
    GooberCooter October 09, 2020

    The comments already here express the feelings of most experienced practitioners. Existing terminology is not inherently discriminatory or racist, it is a matter of context, just as the words black and white do not necessarily have a racial connotation and can simply refer to colors. That said, the angry social just mob seems intent on eradicating everything that can be construed as discriminatory in some sense, no matter how abstract or out of context. It’s not unlike Beavis and Butthead finding sexual inuendo in random comments.

    This movement has been afoot for years, with non-technical experts in the oppressive use of language weighing in. They don’t give practitioners any credit for being able to distinguish language intent and context. Sadly, it’s a battle that seems unlikely to go away. Traditional terminology seems destined to eventually be swept away by the relentless waves of social justice.

    Proposed replacement terminology seems more verbose and less clear, it doesn’t quite hit the functionality nail on the head like traditional terminology. There are going to be a lot of legacy standards like MODBUS that will have to change. It would be one thing if we grandfathered legacy standards and designs, but there will be a push to touch all of this language and respin boards to remove labels from silkscreens. I saw an article a couple of years ago about a government entity in California touching all of its documents to replace the term ‘manhole’ with gender neutral language.

    Does anybody remember Vonnegut’s Handicapper General, and the film Between Time and Timbuktu with the hilarious ballet performance where the dancers were all forced to wear sandbags in the interest of equality? Vonnegut made the point well, mindless and unconstrained egalitarianism becomes a problem at some point.

    Like. Reply
  • Y
    yamaha_yl1 October 09, 2020

    What about giving all network nodes a gender neutral name and prefixing it with “comrade”?

    Like. Reply
  • R
    Richard Nelson October 09, 2020

    What is next, removal of male and female for connectors because the other 50+ “genders” are offended?  X < > Y, Sonoran desert Richard

    Like. Reply
    • R
      Richard Nelson October 09, 2020
      Let's leave political correctness to the politicians. Let's keep politics out of the technical fields.
      Like. Reply
  • V
    vanderghast October 09, 2020

    Early Greeks were having human slaves of ... Greek origin (it was Solon, I think, who abolish slavery to those unable to pay their debt, in pre-classical era). I find it a little bit presumptuous to imagine that there were only black human slaves. I don’t even see why master-slave designation in electronic should be linked to human slavery, even less to racism.

    Like. Reply
  • R
    RioRicoRick October 09, 2020

    These words have already been redefined - they USED TO mean something else!

    Like. Reply
    • R
      RioRicoRick October 09, 2020
      You know, way before ANY of us was even alive! Why don't we ever get a say; why to the wackos and liberals get to dictate to use what we say and do? We must stop voluntarily bowing down to everybody else.
      Like. Reply
      • R
        RioRicoRick October 09, 2020
        Before that it had a different meaning, as well - that is until slavery was invented in Africa by African-Africa people. I guess that's how they describe themselves??? It fits the pattern used here.
        Like. Reply
  • K
    Kmpres October 11, 2020

    I think you guys crying PC foul are jumping off the deep end here.  The problem isn’t so much the word “master” as it is the word “slave”, which does not alway accompany the word “master”.  The word “master” has some perfectly innocent meanings.  For example, a “Master of Science” degree does not have a “Slave of Science” degree equivalent unless one considers himself a “slave of science” which is usually a positive description of his devotion to the subject.  When one “masters a skill” there is no “slave of skill” lurking somewhere in the background unless you consider the skill itself some kind of slave.  Similarly, the “Master-Student” relationship is well established in many cultural education curriculums (no slave there), and the word “Master” is still applied to boys as a title of respect before he reaches maturity in some western societies. Similar honorifics exist in eastern societies. No slaves there, either.  Even the “Master Boot Record” in computer science does not have a “slave boot record” to go with it. I’m all for political correctness but lets apply it rationally.  “Master-Slave” as applied to circuits could easily be changed to “Primary-Secondary” without argument. Lets leave it at that.

    Like. Reply
  • B
    bombard October 11, 2020

    Sorry, but white estonians where in slavery too and this slavery ends two years later after blacks get freedom in USA. And I dont feel that MISO/MOSI is somehow offensive to me.
    Master and slave are terms from long history and if someone feels that they are offensive then there is need for psychiatrian. This is like in Orwell’s “1984” than someone tries to erase words from language.

    Like. Reply