The Big Red Switch really was big and red


In this article on compatibility between the .NET Framework versions 1.1 and 2.0, there is a passing mention of a setting nicknamed the "Big Red Switch".

The power switch on the original IBM PC really was big and red. Well, orange-red. Here's a picture of the power switch on an IBM PC-AT. Decide for yourself what color it is.

In college, the hallway that led to the basement lab where most of the computer science students did their work had a big red switch, a pushbutton, labeled "Emergency power shutoff". Nobody was sure whether it actually was hooked up to anything or was simply a joke, but nobody wanted to take the chance of finding out, either. I remember one evening some people were goofing off with a basketball, and somebody missed a pass, and the ball hit the wall dangerously close to the big red switch. They (and everybody in the lab) immediately realized what had almost happened, and the group sheepishly took their ball outside.

Some time later, the legend of the big red switch was ultimately resolved. The morning after a particularly bad rainstorm, one of my colleagues came into the computing center and explained that he had gone down to the computer lab the previous evening and found it flooded, with water still coming in. Realizing that electricity plus water equals danger, he went over to the big red switch and pushed it. And true to its label, it shut off the power to the lab and the central file server. We were all in awe that he got to push the big red button for a legitimate reason. An opportunity like that comes only once in a lifetime.

Comments (34)
  1. Nathan_works says:

    It was red. And had a hefty, satisfying clunk when you toggled it.

  2. Steven says:

    An opportunity like that comes only once in a lifetime.

    Hmmm… I’m still waiting for that opportunity. Kinda like the emergency break on a train. Can anybody sitting in a train actually have a legitimate reason for using those?

    Then again, it seems somebody’s used the Big Red Switch on the internet in this country (The Netherlands). Over half the country’s lost connectivity at the moment.

  3. James Schend says:

    Just make sure you don’t hit the brake for a medical emergency. The Sounder train into Seattle has that little caption over it, and it makes sense: in a medical emergency, it’s probably in the best interest of the train to make it to the city as quickly as possible instead of stopping in the middle of nowhere and calling an ambulance.

    I used to work at a place with a Big Red Button. We never knew if it worked, either, because it was a 24/7 operation and we never scheduled downtime just to test the button. My guess is that that server room had been re-wired so many times, it probably worked on some of the circuits and not on others.

  4. Richard says:

    I use the emergency brake on a train once.  It pulled up to my station; the door never opened, in spite of me pushing the button, so when the train started to pull out, I hit the emergency brake.

    It appears that it was a faulty door.

  5. Mike Clark says:

    Back in the mid-80s I worked in a data communications shop as a data comm tech and we had a pair of ancient Sperry-Univacs that minded the network traffic.  There was an Emergency Power Cutoff switch there, too, and I remember wondering when they were going to tell me under what circumstances the button should be pushed, but they didn’t.  After three years there I finally asked about it, and was told that several years before some safety inspector had noted the lack of a cutoff switch as a "ding".  There was no budget to install a working switch, so the boss went out and bought a real switch and a real notice sign that he simply glued to the wall in a conspicuous location.  It satisfied the inspectors.

  6. Grant Bowering says:

    I had one of those AT boxes, back in the day!  Good times.

  7. David Walker says:

    I only got to push the big red button near the exit door in a mainframe computer room once, and that was in a controlled test.  

    The electrician doing the building claimed that it had to be a switch that would have to be replaced once it was pushed.  I didn’t believe him, so I called the building inspector’s office for the City of San Francisco, and he said no, it didn’t have to be the kind of switch that has to be replaced once it’s pushed.  I reported this to the electrician, who did it the way I wanted it.  (I was in charge of the mainframe.)

    The test was fine, although the room went dark since the lights were also controlled by the switch, as I recall.

  8. Richard says:

    I’ve still got an AT box somewhere. As I recall, the big red switch was mechanically connected (via a piece of Bent Wire ™, no less) to a normal-sized, white switch on the PSU itself.

  9. Iain says:

    Cue a datacentre-full of stories… To save us all the bother…:

    http://ask.slashdot.org/article.pl?sid=07/05/09/1937218&from=rss

  10. dlane says:

    What’s bad is when the electronic door release is right next to the emergency power off…  That makes you appreciate the wisdom of putting a plastic cover on the power switch.

  11. MadQ1 says:

    I think I still have my budget PC audio amplifier lying around somewhere. It consists of a car amp powered by an AT power supply. IIRC it just needed a 10 Ohm resistor on 5V to stay powered on.

  12. Aaargh! says:

    And oh was the layout beautiful – little fabric loops on all wires to make removing them easier. Wires neatly packed around the sides (…) Those were the times…(..)

    Open up a Serious Computer, e.g. a big ass Sun. They still are like that. Difference is, back in the day, every PC was a Serious Computer.

  13. Mario says:

    Are you sure he didn’t push first, flood later?

  14. CW says:

    At my Secondary School the computer room, full of Acorn BBC Micros and Archimedes machines at the time (http://en.wikipedia.org/wiki/Acorn_Computers_Ltd), did indeed have a big red switch on the wall by the door, unprotected by a guard of any kind. The teacher in charge wasn’t averse to giving it a thump if he thought people were messing about in lessons. Someone once shoved me against it during morning break which nearly ended in me getting lynched by a group of fellow nerds. Happy days!

  15. Fred says:

    The original IBM PC was not an AT.  That came later.  The original was definitely red.

    [I never claimed that the AT was the original IBM PC. (Indeed the fact that I explicitly called out that it was an AT highlighted that I was showing something similar but still different.) I couldn’t find a picture of an original IBM PC power switch. -Raymond]
  16. THING2 says:

    What’s a discussion of the BRS without mentioning the molly-guard?

    http://foldoc.org/foldoc.cgi?query=molly-guard&action=Search

  17. SteveAngel says:

    I take exception to the pictures of the old AT.  In one it refers to the machine as being "close to the base configuration".  That most certainly was not!

    It is indeed an original AT (notice the unique piggyback chips on the motherboard), but it had an EGA graphics card which was rare at that time due to the price of the monitor.

    The parts that really stick out are those two huge memory boards (EMS EEMS and/or XMS).  Those were the days when 256K memory chips went for $10-15 each, and it took 9 to fill a bank.  Just a single meg was 36 separate chips.  It was rare to see a machine with just a single board, let alone two of them.

    The images are just large enough to be tantalizing, but fuzzy enough to maintain the mystery.

  18. Robert says:

    Note that although the buttons were red when new, the colour in the plastic would have faded over time, resulting in an orange-red button.

    So any recent photos of an old computer would show orange-red.

  19. Mr Cranky says:

    There have been many times when Mr Cranky really wanted a real power switch when Windows decided it wasn’t yet time to power down when I pushed the little request button that is all we get nowadays.  WTF?  If I wanted permission, I would’ve used the Start button, duh!  Or much worse, is out to lunch and not polling the button any more.  I eventually found out about holding it down for 11.3 seconds, or whatever.

    Anyway, I heard that the big red switch became a medium-sized white switch when hospitals objected to the BRS.  Something about their procedures in emergency situations required them to slap all big red buttons and switches in the room.  I do surely hope that not many people were dependent on a PC to keep their vitals going.

  20. no-one says:

    The thing with the basket ball reminds me of our college refectory. There’s an "almost vandalistic behavior" element to it.

    Our college refectory had a very high ceiling. High enough that you’d need a scaffold to get to it. It was lined with those suspended soft fibre tiles.

    Anyhow because times were different each table had a fresh aluminium ashtray installed each time the cleaner came around and cleaned the table.

    The thing with these ashtrays was that they were pressed out of aluminium foil. The foil it’sself was about four or five times the thickness of regular baking foil, and coloured on one side, in about six colours.

    These trays could be flattened out to a perfect circle, with a moderately sharp edge. They made excellent frizbees.

    What never ceased to amaze me was how many of these things had been embedded in the ceiling. You would certainly loose count.

    That nobody ever came along and removed them, didn’t really matter, because they actually looked much nicer than the tiles.

    Nevertheless, there was a sign saying you shouldn’t do it!!!!

  21. Aaargh! says:

    > I had one of those AT boxes, back in the day!  Good times.

    Same here, if you turned that thing on, you *knew* it was on.

  22. Morten says:

    Old HP machines (XT or AT, can’t recall ATM) had a Stick(tm) ‘twixt the button on the front panel and the real switch *inside* the PSU located at the back, so that when the button was pushed the action was transferred mechanically to the swith. Looked quite goofy but apparently it was better than pulling wire around the housing. And oh was the layout beautiful – little fabric loops on all wires to make removing them easier. Wires neatly packed around the sides. And the mother of all full-length 2-side circuit boards for a graphics card. *sigh* Those were the times… not… ;-)

  23. Anon says:

    "There have been many times when Mr Cranky really wanted a real power switch when Windows decided it wasn’t yet time to power down when I pushed the little request button that is all we get nowadays.  WTF?  If I wanted permission, I would’ve used the Start button, duh!  Or much worse, is out to lunch and not polling the button any more.  I eventually found out about holding it down for 11.3 seconds, or whatever."

    Most machines will cut the power in hardware if you hold the button down for more than 10 seconds to let you shutdown a machine where some driver or service is wedged. It will corrupt the disk though, so chkdsk will run on the next boot.

  24. NotTheCourier says:

    Our data centre has a big red switch with a sign that says "emergency power cut-off".  So that it isn’t accidentally pressed (say, with a basket ball), it’s in a Perspex box with a round Perspex window hanging off a screw.  To press it, you need to swing the round Perspex window out of the way, reach into the box and press.  Needs two hands to press it.

    Or, you need to be a courier who assumes it’s the exit switch for the doors, but doesn’t ask himself why it’s in the box with the sign that says "emergency power cut off".

  25. Dan says:

    http://www.turnofftheinternet.com/

    "Anyway, I heard that the big red switch became a medium-sized white switch when hospitals objected to the BRS.  Something about their procedures in emergency situations required them to slap all big red buttons and switches in the room.  I do surely hope that not many people were dependent on a PC to keep their vitals going."

    This procedure seems a little puzzling to me.  You’d think with peoples’ lives hanging in the balance in emergency situations, they’d be more precise about training which devices should be shut off and which shouldn’t.  I am not comforted.

    "Or, you need to be a courier who assumes it’s the exit switch for the doors, but doesn’t ask himself why it’s in the box with the sign that says "emergency power cut off"."

    Ouch… >_>

    In my experience most public access doors will open if you push, pull, or turn a handle.

  26. > Our data centre has a big red switch with a sign that says "emergency power cut-off".

    It could be this one from APC:

    http://www.apc.com/resource/include/techspec_index.cfm?base_sku=EPW9

  27. DaveShaw says:

    I remember my at work experience visiting a call centre. It was a quiet day, usual trickle of calls then all of a sudden a missive influx of calls.

    Hundreds of customers could not login.

    Finally we got the bottom of it.

    Someone in a data centre somewhere lent over to place a box on the floor and as he bent over his ass stuck out and pressed the "Big red button". I laughed anyway. ^_^

  28. The first technical writing project I worked on was for a BRB emergency shutdown feature on an electronic test system. The senior writer told me it stood for ‘big red button’.

  29. Jeff Read says:

    The Big Red Switch on early IBM PC and PS/2 models was either part of the power supply, or it mechanically activated a switch on the power supply via a metal lever inside the computer case.

    Now that’s advanced power management!

  30. Mike Anasi says:

    I worked in a steelworks BOS shop. This shop had two BOS furnaces side by side (one being relined while the other is used). BOS works by injecting a supersonic oxygen jet into the motlen iron bath to burn off most of the carbon and make steel.

    One day, the lance started to retract before the oxygen shut off. This does all sorts of damage. There is a Big Red Emergency Cutoff button in the middle of the console. Hit that, nothing. Hit it a few more times. Now what?!?!?

    At this point logic kicked in. There are two furnaces side by side, with side by side control desks. Run over, and hit the switch of the OTHER desk. Oxygen cuts off.

    So it had been cross wired for a long time, and no one had ever had to hit the switch until it mattered…..

  31. -alexander says:

    i remember the original IBM PC… and the myriad of early computer designs (Timex Sinclair, Commodor, Apple IIe, etc.) with fond memories! As for the BRS, i actually still have some! i salvaged a few off old machines before they were tossed. i even have a stack of old processors. There’s just something nostalgic about them!

  32. cabinet.exe says:

    Not all IBM AT Clones had the red switch.

    I found a Tandon AT and a SIEMENS PC-D2

    which had smaller black switches on the back.

    I found 2001 an empty IBM AT case and a red switch power supply and converted it to a 486.

  33. Andrew says:

    "Kinda like the emergency break on a train. Can anybody sitting in a train actually have a legitimate reason for using those?"

    "a large piece of metal coming up through the floor" qualifies?

    http://en.wikipedia.org/wiki/Eschede_train_disaster

    And a lot of stories about pressing BRBs:

    http://thedailywtf.com/Articles/The_Big_Red_Button.aspx

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