Bill Gates made many exceptional decisions while he was leading Microsoft to immense success. He did, however, make a few errors.

Bill Gates chats with David Rubenstein, Harvard Campaign co-chair.

One of those was the idea of using “Control-Alt-Delete” —  initially designed to efficiently reboot a computer — as a way to log into Windows.

During a fantastic talk last week at a Harvard fundraising campaign, Gates admitted that it was a mistake to force users to use hold down “Ctrl+Alt+Del” to log into their computers.

“Why, when I want to turn on my software and computer, do I need to have three fingers on Control, Alt, Delete?” asked David Rubenstein, Harvard Campaign co-chair. “Whose idea was that?”

Gates then explained why Microsoft decided to implement the command.

“You want to have something you do with the keyboard that is signaling to a very low level of the software — actually hard-coded in the hardware — that it really is bringing in the operating system you expect, instead of just a funny piece of software that puts up a screen that looks like a log-in screen, and then it listens to your password and then it’s able to do that,” Gates said.

[Follow-up: The rest of the story: Control-Alt-Delete inventor didn’t expect it to be widely used]

gatesharvard212The Microsoft co-founder said that there was an option to make a single button for such a command, but the IBM keyboard designer didn’t want to give Microsoft a single button. So Microsoft decided to use “Ctrl+Alt+Del” as a way to log into Windows.

“It was a mistake,” Gates said, drawing a big laugh from the crowd.

David Bradley, a designer of the original IBM PC, is responsible for inventing the “Control-Alt-Delete” command to reboot a system. He famously poked fun at Gates on stage during IBM’s 20th anniversary of the IBM PC.

“I may have invented it, but Bill made it famous,” Bradley said.

A decade later in an interview with CNET, Bradley said he didn’t really know why Microsoft decided to make his invention their log-in command.

“Why they used it for the log-in also, I don’t know,” he said. “I guess it made sense for them.”

I recommend watching the whole Gates talk, which helped celebrate the launch of the Harvard Campaign. Rubenstein does a really good job guiding a discussion that touched on a number of interesting topics from Gates’ early days at Microsoft to his work at the Bill & Melinda Gates Foundation, all the way to how he first met Melinda and how many more years he plans on working for.

His comments on “Control-Alt-Delete,” start at 16:30. Watch the entire talk here.

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  • Larry Osterman

    Many years ago, I asked the Windows architect who chose control-alt-del as the logon sequence and he indicated that it was the only key combination that wasn’t already being used by some application. And of course applications didn’t use it because it would have caused the computer to reboot.

    • Michael

      I remember asking this question too, but I got a different response. ctrl-alt-del normally reboots a machine, but if you create a boot loader and HAL to capture keyboard input before you run it to the hardware, you can intercept ctrl-alt-del and do with it what you want. So as Gates says, if an application loaded and looked/felt like Windows, and said “enter your password here” you might enter it and it would capture your password. However, if you require ctrl-alt-del for login & it’s conspicuously displayed at the login screen, and the bogus application didn’t have bootldr/HAL and secure winlogon system, ctrl-alt-del would reboot the box.

      • guest

        You, sir, have it correct.

        When making the First MSFT Ergo keyboard, we explored revisiting this, but by this point Ctrl-Alt-Del was deeply embedded in WIn95/NT, and got nixed at the Silverberg/Balmer/Gates level.

      • dabble53

        Ummmm….sorry, but the keyboard goes to the hardware/firmware BEFORE it goes to any HAL or OS or generally loadable software.
        What the hardware/firmware do with it, is up for discussion, but it definitely sees it first and can take whatever action it likes before any bootldr/HAL/OS/etc has a clue it’s been pressed.

        • guest

          You obviously think you know what you’re talking about, but you don’t.

          • dabble53

            Let’s see….I’m an electrical engineer. I’ve worked with computers and software on all types of equipment for over 30 years. How is it you think a key-press gets delivered to the software (the OS?) It doesn’t just magically appear in the code. It travels over a little thing like a wire (HARDWARE) or via some wireless link that talks via (you got it, HARDWARE.) However it gets from your keyboard to the computer at large, it ends up generating an interrupt (HARDWARE) that vectors to some interrupt handler (the software link that may or may not be a HAL piece of code – could be a BIOS piece or most anything else)
            So, yes, I obviously DO know what I’m talking about, and apparently one hell of a lot more about how computers and software actually work than you do.

          • rahul

            Nailed it.

          • guest9000

            other guest is bill gates. he think money = experience

        • xor

          While dabble53 is correct in that the hardware/firmware could do any action with a keystroke before it goes to any HAL or OS in practice the firmware within a keyboard is not downloadable. Thus you are stuck with the scan codes it generates. If you can find a keyboard that uses an external ROM or PROM then you could replace that to customize a keyboard.

          It would make more sense to create a device that looks like a USB keyboard and you plug a USB keyboard, PS/2 keyboard or even the old 5-pin DIN keyboard into it. That device can intercept various keys.

          With both the 5-pin DIN and PS/2 versions the keyboard and computer talked with each other using essentially RS-232 though with a twist in that it was clocked and not asynchronous, that the data wire was bi-directional, and that it ran at 5 volts instead of +/- 12. If you ignore all that then it’s RS-232 and could be clocked at any data rate from about 20khz to 30khz.

      • OldEagle

        Of course DOS did nothing to protect interrupts, hardware, etc. so it was easy for a DOS application or TSR to hook ctrl-alt-del to prevent a reboot just like Windows.

        This is why sometimes you have to use the power switch.

        This is how DOS disk cache programs flushed the cache on a reboot.

        This is why many PC clones added a reset button near the power button.

        • dabble53

          You are correct. It wasn’t until the OS started running in protected mode that interrupts and all the rest had any protection. Not that earlier PCs had the ability to run in protected mode if they wanted.

    • CityGuySailing

      This is not true. I have had IBM PCs from the beginning, and after studying the BIOS code, it is the lowest of software interrupts running at ring-0. The lowest level of interrupt. This is designed to stop and take control over whatever other tasks are running if at all possible. Sure, you can hang other handlers on top of this (TASKMAN.EXE for example), but it all comes down to decisions made during the original design process of the IBM PC in 1978 or 1979.

      • dabble53

        I think the story wasn’t about how ctrl-alt-delete works (the ring-0 interrupt), but that this interrupt was used to initiate the log-in process of the OS.
        This only works because the OS (Windows in this case) installs the appropriate piece of software for the interrupt vector to call. Anything (or nothing) could have just as easily been installed.

    • Edward Sheppard

      I am sure this is it. It is a very clever choice and Gates isn’t stupid so I’m sure he means IBM made a mistake by not giving Microsoft a special key for it.

      • Another guest

        Exactly. I am not sure how anyone got the impression that he was saying it was a mistake on Microsoft’s part. In context it seems clear he is saying that the mistake was that IBM did not include a separate hardware logon button.

  • investor

    Is it just me or is he gradually looking more like Warren Buffet?

    • bob

      I was thinking Larry King.

  • wilmark johnatty

    Why is this a mistake – if you didnt have 3 fingers you could use sticky keys. Rebooting the computer is not something that you want to do by accident and having three keys to do it (like many other shortcuts) is not a bad way to do this. Having a dedicated button would have introduced other problems, like accidental use etc. This just sounds like an antiwindows wise crack.

    • OldEagle

      This is about the decision to use ctrl-alt-del for the Windows login, not the original PC reboot decision.

      • velvetjoneslives

        If that is the case, why blame IBM and their keyboard? The original Apple II had a single key reset and they changed that in the II Plus because it was too easy to hit by accident. IBM wanted the reset sequence to be hard for that very reason.

    • TMC

      So you feel that the person who said this- Bill Gates- is anti-windows?

  • Young


  • Yorel

    That is to avoid spoofing or phishing. A malicious app can fake windows login screen to get users password, if cntr+alt+delete is pressed then either original login page comes up or task manager comes up if malicious app showed a login screen.

    • microsoftee

      A malicious app can also hook to Ctrl+Alt+Del interrupt likewise Windows OS do. Don’t be in dark, everything is possible. Every lock has way to break.

  • Dejay Clayton

    I feel privileged to know what a hardware interrupt is. And old.

    • dabble53

      Too bad the world kept the Intel interrupt operations instead of switching to the much more logical Zilog (Z-80) mechanism of chaining interrupts.

  • JohnNiles

    I like ctl-alt-del. I use it frequently. Lets me know I am talking directly to the computer, and not to whatever software has just locked up my machine and screwed up my thought process.

    • martian packets

      And what do you say when you talk directly to your computer?

      • Carl Pham


  • Ack

    If they did that, then everybody would now give Bill Gates the “one finger salute”.

  • Ommar A

    how does the riches person in the world cant get glasses that don’t fall every 5 seconds lol

    • kone

      at least he uses proper grammar.

      • Rob Grainger

        Glass houses and stones spring to mind.

      • Rob Grainger

        Glass houses and stones spring to mind.

  • anonymoose

    I always thought they did this to edify people of the “3-finger” salute. In my opinion (and I do a lot of IT support), it actually did teach/remind people that those 3 buttons are like a gateway to the OS’s “command center.” Pretty serendipitous.

  • Hans B PUFAL

    Has no one caught the errors is the dates Bill gives for the founding of Microsoft. Starting at 5:58. Bill states that Microsoft was founded in 1979 and contrary to his thoughts at the time it would have succeeded even if started “in 1980 or even 1981” This is clearly wrong. Had MS been started in 1981 they would have completely missed the boat with the IBM PC and the world of computing would have been changed.

    The correct dates are 5 years earlier, Google tell us that MS was founded in Albuquerque, New Mexico on April 4, 1975. Now Bill’s statements make more sense, starting in 1976 or 1977 might not have made a huge difference but even that might be contested since the delay would most likely have caused some other entrepreneur or company to create the Basic interpreters which were fundamental to the launching of the early personal computer revolution and MS as a new entrant might not have succeeded.

    The whole Ctrl-Alt-Del confuses two functions separated by several years. Ctrl-Alt-Del was originally created bu IBM to reboot the 1981 IBM PC. As such Microsoft had no say in the matter it was a BIOS function and the responsibility of IBM. The use of Ctrl-Alt-Del to restart or log-on to Windows came years later and is covered in this article

    As a computer historian I am very sensitive to factual errors. Bill Gates makes quite a few in this video and that saddens me.

    • YaanG

      I worked with a guy who was on the original IBM PC development team, and he told me that the hardware guys wanted to put a reset button on the keyboard, because they knew they would need it occasionally. The IBM brass nixed the idea because they thought it would look bad to have a reset button. So they thought of ctrl-alt-del as a workaround.

  • Timothy Collins

    I don’t get it….ctrl-alt-del is just a keystroke combo. It’s not, in my mind, any different than any other keyboard combo on other OS’s to do the same thing…

    • PhasmaFelis

      The first time I saw “Press Control-Alt-Delete to log in” (on my freshman roommate’s desktop) I thought it was a joke. I honestly thought that I’d press Control-Alt-Delete, and the computer would reset, and he’d laugh at me, because any idiot knew that Ctrl-Alt-Del doesn’t do anything but reboot the machine. It was like saying “Unplug the power cable to log in.”

      That was then, of course. Now, it’s just kind of weird that you have to press three different keys at once to do something as basic as logging in to an idle computer.

  • Michael Hazell

    Wasn’t this discontinued after the Windows XP release? I haven’t seen myself have to use CTRL + ALT + DEL when having to log into a networked Windows Vista or 7 PC.

    • dajve

      It’s optional for Vista / 7 / 8. Typically you won’t see it in a domestic PC, particularly where it’s in a single-user environment – but the option is still there and is commonly applied via group policy in business settings.

    • nohbody

      It depends on what the login policy is. Generally, a single-user environment would not have it enabled, (I run XP on my netbook and it defaults to not showing it) while a networked, multi-user login environment does have it as a recommendation to make sure the user is is physically present at the terminal being logged into.

  • mtthwbrnd

    Rubbish! The three finger reset is an Illuminati symbolism for worshipping the devil – and they got you all doing it! Always turn your computer off at the switch and avoid devil worship. Yes it is easier to just say “I can’t be bothered to turn it off and on again at the switch, and sit through the disk scan”, but that is not going to help you while you boil in excrement for eternity in the bowels of hell!

    • Elkar

      I don’t think there is enough LSD and weed in this world to fathom what you wrote.

      • Steve Skubinna

        I think its pretty clear. Only a minion of Satan would question it.

        • Carl Pham

          Nonsense. Questioning statements, even by The Opponent, is a privilege not granted to mere minions. You have to be Oberhauptdemon Level 2A or higher.

  • Mario Boulet

    It’s a little bit better than Texas Intrument 99 4a with his « reset button » and Commodore with his hairpin to put behind the keybord where we put cartridge game to make reset.

    • TheShaz

      For the C=64 it was SYS64738
      My 1st computer was the TI99/4A. But after that, several C=64’s, 128’s and Amiga’s. Amiga was fun, instead of the BSoD of Window’s it would “Guru”

      Brings back memories.

  • DarthDana

    Why not Control-Alt-Delete? One task required before logging in is to make sure the keyboard buffer is clear. Ctrl-Alt-Del was a combination already coded to do this. I don’t really see why another combination would have been better.

    • hurtin1

      Yeah, I’m not sure what’s with the antipathy toward Ctrl+Alt+Del. The only real drawback to it as far as I can see is the association with your —-ing computer not —-ing working in the 1990s.

  • Jon Peterson

    For those who don’t want to watch the whole thing, the Ctrl + Alt + Del bit starts around 16:45.

  • P.L.

    The Ctrl-Alt-Del Rubenstein asked wasn’t the original Ctrl-Alt-Del. It was introduced in Windows 2000 as a security feature as Gates described. But as explained by him, three keys wasn’t needed.

  • Tal
  • dwpittelli

    I wouldn’t want a 1-button, or even a 2-button, reboot command. You don’t want it to be possible to hit it by mistake while typing sloppily.

  • Kfredrick72

    Make it too easy and users could reboot by mistake. I do wish it wasn’t so difficult to do with one hand. Basically it is a non-issue though.

  • dsstrainer

    C-A-D makes perfect sense. It wasn’t a mistake, it was genius by David Bradley

  • RockThisTown

    Bill Gates admits Control-Alt-Delete was a mistake

    Windows is/was a mistake, too.

  • koblog

    …as if Harvard needs to raise funds.

  • koblog

    …as if Harvard needs to raise funds.

  • mtthwbrnd

    Microsoft made a much bigger mistake, by the way. It is called Windows 8! Specifically the way that every time you touch the mouse pad on your laptop, some other stupid screen appears telling your what the weather is like. It cannot be disabled. NOBODY can fathom why the hell they did this. It is the reason why I will never upgrade to Windows 8. Because it is literally unusable.

  • U S A U S A U S A U S A U S A

    Control gay kill!

  • U S A U S A U S A U S A U S A

    And suck it and fuck you!

  • U S A U S A U S A U S A U S A

    Alts are gay.

  • U S A U S A U S A U S A U S A

    If you are “alt” you are going to death row.

  • U S A U S A U S A U S A U S A

    Alt tab soda.

  • U S A U S A U S A U S A U S A

    Meta plus mmmmmm.

  • richard40

    Using cntrl alt delete to interrupt a process and do a shutdown/reboot made a lot of sense, since it is too easy to accidentally hit a single key and interrupt a process you don’t want interrupted. I remember that was a constant problem with the old apple 2 reset button, especially since they put it right next to the return key, which made it really easy to hit accidentally. Where Gates went wrong was requiring people to hit cntrl alt delete to initially bring up the system. At that point you have a screen with only one thing you can hit to go on, so it may as well be an easy key to hit.

  • microsoftee

    A malicious app can also hook to Ctrl+Alt+Del interrupt likewise Windows OS do. Don’t be in dark.

  • Mike Greenawalt

    I must be losing it somewhere. I do not recall ever using ctrl-alt-del to login to Windows. But then I did not use Windows very much before XP. My worklife tended to be done on terminals attached to minicomputers – DEC, Sun, Burroughs, Perkin-Elmer, …

  • BruntLIVE

    who cares, no one on this board has made anything better. you have a choice, geeez really people. Get a life

  • Christian Benesch

    He only admits that it was IBM’s mistake. :-)

  • Leslie

    I do not deny Apple has issues with
    corruption and the slave labor they are said to employ in poor countries
    but personally for anyone to be so uninformed
    (or not care) about exactly what they are supporting when buying
    Microsoft products just blows my mind, I think we all would agree that
    our vote with $ has far more impact these days then our vote at the
    ballot box, right? Do you know WHO Bill Gates really is? Do you know
    what he is up to? He is neck deep in politics, Common Core, Monsanto
    (GMO foods that produce pesticides within the DNA of the plant which
    means when we eat them and the animals we eat consume them, we are
    in-fact eating pesticide ourselves, not to mention GMO’s are killing off
    them bee populations worldwide and when they are gone, so are we).
    GMO’s are destroying the soil where they are planted so only GMO crops
    will grow, not to mention cross pollination is a big issue and Organic
    Farmers who want nothing to do with GMO;’s are being sued by Monsanto
    when the seeds blow over and start growing on land where farmers did not
    pay for the evil seeds, so not only is the organic crop contaminated,
    they are sued on top of it.

    Bill Gates is also deeply involved
    with vaccines that are linked to side effects that include death, only
    most of these vaccines are being tested in poor countries and the
    tragedies that surround the vaccines are not reported by mainstream
    media, as a matter of fact, very little that has any significant value
    is reported on ANY TV news network. Bill Gates loves to do lectures on
    population control, he has outright stated he thinks vaccines can be
    used to achieve this and he is creating a monopoly on agriculture while
    destroying farmers, bee’s and the earth in his path, Monsanto FYI is
    directly connected to the company that created agent orange.

    Personally, I do not care how cool anything is, if Bill Gates is
    profiting from my purchasing it, forget it, he is one of the most vile
    creatures among us (there are plenty more)

    • Guest

      Them bee populations…..

  • The HED

    Seems like an obvious way to protect people’s credentials. If I’m being displayed a false login screen by some malware, then clicking ctl+alt+del should technically interrupt everything and give me some options. If I’m at the legit login screen, then pressing those will let me proceed. I’m not sure if that was part of the reasoning or not.

  • Sten2005

    So perhaps you can get him to admit that the abandonment of the VB6 programming language in 2002 was a mistake ?

    Because now, in 2014, Microsoft have just announced they will continue supporting VB6 programming until ‘at least’ 2024.

    VB6 continues to run on Windows 7 and Windows 8/8.1 and will presumably do so on Windows 9.

  • xor

    Ctrl-Alt-Del to reboot was coded into the BIOS which is the software layer that talks with the hardware. MS-DOS called the BIOS to check for and to get keystrokes. If the BIOS detected Ctrl-Alt-Del then it rebooted the machine rather than returning a keyboard code back to MS-DOS.

    Windows 1.0 to 3.1 were layered on top of MS-DOS meaning the BIOS was still in control of things and Ctrl-Alt-Del worked the same as it did under MS-DOS.

    Starting with Windows 95 Windows has its own BIOS that talks directly with the hardware. Microsoft could have done anything it wanted with Ctrl-Alt-Del. Had they ignored that combination of keys it’s likely it would unknown to most computer users today. Instead, Microsoft decided to have Ctrl-Alt-Del activate special functions such as the login screen, the Windows Security window, etc. They never assigned a keyboard code to it and instead it has been a way to activate special dialog boxes.

    Besides Ctrl-Alt-Del the original IBM PC BIOS had two other special key combinations. The first was was activated by pressing the Pause button without a Shift, Ctrl, or Alt. When the BIOS detected the Pause key it disabled interrupts and went into a hard loop watching the keyboard hardware for any key-down. When it saw a key it left the loop. In the MS-DOS era I imagine Pause was mainly used by people playing games who wanted to suspend things. When they wrote the BIOS that’s built into Windows-95 Microsoft chose to ignore the Pause key and it’s been ignored ever since.

    The BIOS handled Ctrl-Pause in a somewhat special way. With most keys the BIOS gives you one code when you press a key and another code when you release it. MS-DOS ignored the release events. Ctrl-Pause was an exception in that there was only a key-down event which returned ASCII 7F. There was no key-up event. The reason for this was old style Teletype machines had a special key off to the right of the main keyboard called BREAK. When you held this down it opened the signal wire that connected your Teletype to the remote Teletype and held it open. On the far side the receiving Teletype would go into a mode where it was continuously getting ready to print a letter. It would go chung-chung-chung-chung… and was a way to get the attention of the remote operator.

    A teletype also had a bell which you could ring but the chung-chung-chung also created a considerable amount of vibration and got more attention than a “ring” of the brass bell inside the teletype. Anyway, Ctrl-Pause could have caused an event similar to the Teletype’s BREAK. However, the IBM PC lacked a brass bell and lacked a large electric motor attached to enough weights that you could cause the entire 75 pound Teletype to go “chung.” Thus, for nearly all of the history of the IBM PC on to Windows, etc. Ctrl-Pause has done very little though it still returns key code 7F.

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