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Boot manager failed to find OS loader 0x490

October 22, 2010 6:11 pm by

Background to the near catastrophic event

Last night, I was modding my Motorola Droid with this sick theme called DarkEdge, to prepare to sell it to a lucky buyer.  In order to remove my Google account from the phone, however, required me to factory reset the phone.  Well, that turned out to not be a good idea because DarkEdge tampers with several files that custom ROMs normally don’t touch [since DarkTheme is also a skin, not just a custom ROM], and as a result, I was stuck in a force-close loop.  Luckily, I can still turn on USB storage so I thought that to solve this simple problem would be as simple as downloading an file and booting into recovery to flash the firmware.  However, all the different ones I tried [FRG22d, CM 6.0, etc.] all failed the signature check, so the only way to go from here is to flash a .sbf file, which I have yet to do.

Catastrophic event

That was the background to what I’m really getting to because downloading all those files from around the internets caused Microsoft Security Essentials to raise a flag that it detected a trojan on my computer!  I have never gotten viruses/trojans/worms before [at least, not that I have noticed :P], so when I was reading the description of this trojan, my computer suddenly shut down for no reason!  When I tried to boot up again, it went straight into the Windows 7 Recovery Mode.  It ran an automated startup repair, which I thought, OK good..usually this will just fix the boot sector or MBR and I’ll be on my merry way.  However, this time around it threw the error “Boot manager failed to find OS loader” with “Error Code = 0x490”.  Thus, when it restarted I was just brought back into the System Recovery Mode, and it did the same exact thing.  Over, and over.

Side note: I divided my HDDs into three partitions: OS, Applications, and Data.  I knew that in the event of catastrophic failure of the OS, setting up these partitions will allow me to retain my data if I have to reformat.  However, what I never knew was if I were to re-install the OS would I be able to not have to re-install all my applications.  If someone knows, please do tell.

I started freaking out because I never had this problem before, and I did not want to reinstall all 100 [exact, yes for real] applications that I have on my desktop.  System restore also did not work.  So, I opened up my laptop and began to search for answers online using my strong google-fu.  After trying multiple solutions, some of which are bogus, I finally found the correct one that allowed me to type this up on my desktop.  I am writing this down for posterity and to hopefully have this correct solution reach out to more folks who are suffering the same problem.  I will definitely be more vigilant with my backups and system recovery images from now on.


This is the link to the thread I found the answers, for reference and citation.  Kudos to momominimo.

If you don’t have your Windows installation disc:

  • Try and cancel the automated startup repair, once you get it to stop, click the link to go to more advanced diagnostics and repair
  • Choose your language
  • You will have to sign in to an account on the computer to verify ownership.
  • Select the option to open up a command prompt
  • You will be running bootrec.exe along with some options, which will depend on your situation.
  • Take a look at the different options below you can run with bootrec.exe to determine which ones you might need to run
  • For me, I ran “bootrec.exe /fixmbr” (without quotes), which you should then see a success message, and then “bootrec.exe /fixboot” (without quotes), which you should see a success message as well.
  • Once done, type the word “exit”, and restart.
  • Hopefully it should boot up now 🙂
  • If you do have your Windows installation disc: (from hereon copy and pasted from source)

  • Put the Windows Vista or Windows 7 installation disc in the disc drive, and then start the computer.
  • Press a key when you are prompted.
  • Select a language, a time, a currency, a keyboard or an input method, and then click Next.
  • Click Repair your computer.
  • Click the operating system that you want to repair, and then click Next.
  • In the System Recovery Options dialog box, click Command Prompt.
  • Type “Bootrec.exe” (without quotes) along with the option that you want to run, and then press ENTER.
  • The commands I ran were (without quotes) “bootrec.exe /fixmbr”, and “bootrec.exe /fixboot”.
  • Type the word “exit” and restart.
  • Bootrec.exe Options


    The /FixMbr option writes a Windows 7 or Windows Vista-compatible MBR to the system partition. This option does not overwrite the existing partition table. Use this option when you must resolve MBR corruption issues, or when you have to remove non-standard code from the MBR.


    The /FixBoot option writes a new boot sector to the system partition by using a boot sector that is compatible with Windows Vista or Windows 7. Use this option if one of the following conditions is true:

    • The boot sector has been replaced with a non-standard Windows Vista or Windows 7 boot sector.
    • The boot sector is damaged.
    • An earlier Windows operating system has been installed after Windows Vista or Windows 7 was installed. In this scenario, the computer starts by using Windows NT Loader (NTLDR) instead of Windows Boot Manager (Bootmgr.exe).


    The /ScanOs option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option displays the entries that are currently not in the BCD store. Use this option when there are Windows Vista or Windows 7 installations that the Boot Manager menu does not list.


    The /RebuildBcd option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option lets you select the installations that you want to add to the BCD store. Use this option when you must completely rebuild the BCD.

    Filed under: General — Tags: , , , , , — Jesse Chen @ 6:11 PM


    Jesse is a software engineer at Facebook, who just graduated from UC Berkeley. Passionate about mobile technology and entrepreneurship, he started his own blog as a home for his tutorials, projects, and random thoughts. Follow him on Facebook to stay updated on his latest tutorials and projects.

    Motorola Droid vs. Droid X Benchmark Tests

    July 25, 2010 11:22 am by

    Quadrant Standard Benchmark

    In this video, I ran the Quadrant Benchmark test on both the Motorola Droid and the Droid X at the same time.  The Quadrant Standard benchmark tests the CPU/GPU by conducting a variety of arithmetic that stress the CPU, memory throughput tests, I/O database read/writes, and running short graphic animations to see how many FPS the device can handle.  In the end, the data is sent to their servers and a score is calculated based off all those tests.  They show your device’s score compared to other devices in a bar graph to see how your device pits against others.  In my tests, the Motorola Droid that is running at the standard 600MHz, android 2.2 froyo scored 874, which is just above the average score for a Samsung Galaxy S running 2.1 eclair.  The average score for a Droid running 2.1 is really low in the charts, scoring 2nd to the bottom so one can see the drastic boost in speed that an android device gets when it updates from 2.1 to 2.2, because of the JIT compiler that is introduced in 2.2.

    The Droid X, however, scored a whopping 1263 in this video, and that is just shy of a Nexus One running 2.2.  So, although the Droid X is running 2.1 eclair, the 1GHz OMAP 3630 processor is super fast.  One can only imagine how well the Droid X will score when it is updated to 2.2.  It will be off the charts, literally.

    Linpack for Android

    Linpack for Android benchmarks your smartphone by calculating how many megaflops it can calculate in a given amount of time.  I ran a series of 5 tests to get a better understanding on how each device stands compared to each other.

    Droid: 9.129 | Droid X: 8.328

    Droid: 9.632 | Droid X: 8.328

    Droid: 9.598 | Droid X: 8.315

    Droid: 9.615 | Droid X: 7.834

    Droid: 9.598 | Droid X: 8.328

    As you can see, the Droid consistently calculated more megaflops than the Droid X.  So surprisingly, in this benchmark, the Droid takes the cake and goes home with the money.  I can guess that this is a test purely stressing the CPU, which makes it more even for the Droid.  However, if it was that simple, the Droid X should have easily won because it’s processor is 1.6x faster than the Droid.  Do keep in mind, though, that the Droid has a JIT compiler, which somehow plays into this benchmark, making it compute megaflops faster 😛  I wish I can explain the details in whole, but unfortunately, I don’t really know much more than that.

    I will update with another video when the Droid X gets 2.2 froyo, and then we’ll see how it pits against the Motorola Droid.

    Filed under: Android,Reviews — Tags: , , , — Jesse Chen @ 11:22 AM


    Jesse is a software engineer at Facebook, who just graduated from UC Berkeley. Passionate about mobile technology and entrepreneurship, he started his own blog as a home for his tutorials, projects, and random thoughts. Follow him on Facebook to stay updated on his latest tutorials and projects.

    Droid X Review

    July 17, 2010 10:07 pm by


    So I have been using this phone for almost 3 days now.  This review will go over the hardware and software of the Droid X briefly and what my impressions are.  This isn’t a technical review with hard numbers and specs – I’m going to try to write this from a layman’s point of view to make it more relative to the average reader.  This is a review that I promised for Jeff!

    Droid X is the new flagship phone for Verizon, their answer to Sprint’s exclusive, HTC Evo.  The HTC Evo for Sprint is heavily compared to the Droid X because they both have a massive 4.3′ screen and they both are their respective carriers’ exclusive top-tier android phone.  The Droid X is 199$ after rebate with a new contract.  The first batch is supposedly sold out and the next batch is due to ship July 23, 2010.


    First thought: Wow, this screen is big.  For people with small hands, this phone might not be for you.  I would say my hands are average-sized and using the phone one-handed is not too difficult.  The phone is also very thin, with the thinnest part being perhaps as tall as 5 quarters stacked high [does that comparison even help?].  The weight is also deceivingly feather-light, holding it in my hand feels very natural with that “hump” on the top.

    Microphones + Physical Buttons: The Droid X comes with three mics: one in the front for phone calls, a noise-cancelling one on the top, and one in the back for when you record video.  The phone only has 4 physical buttons besides the 4 small shortcut keys below the screen.  They are the: power/lock, volume up, volume down, and camera button.  They made the volume rocker smaller than the Droid, which I think is a disappointment because since the phone is much bigger, it is harder to reach and feel for the volume rocker so in my opinion, it would make sense to make it bigger to be more ergonomic.

    Physical Shortcut Keys: Traditionally, android phones have the 4 shortcut keys on the bottom of the screen as “soft-touch” keys, where you don’t need to press any buttons, you just have to lightly tap the area to execute the shortcut.  With the Droid X, they changed it and made them physical buttons.  I do like the tactical feedback and I like knowing whether I pressed the shortcut or not.  With the Droid, sometimes I think I pressed Home, for example, but the screen stays the same and I have no idea if the phone really registered my input at all.  With physical buttons, it takes away the ambiguity.  Physical buttons give you tactical feedback which is more preferred, but using the “soft keys” enable to you execute the shortcuts faster since you just have to tap, rather than press and release.  In all, both ways have their pros and cons, I am happy with either one.

    Screen Size + HDMI Port: The screen is 4.3′ [diagonal measurement] as mentioned before, and I think this should be as far as how big screen size on phones should be.  This is a good screen size for a phone that you will use heavily for browsing the web, watching videos, and games.  For me, the 4.3′ screen really stands out when I am reading my Google Reader and watching youtube videos.  The Droid X is advertised as a multimedia phone so it includes a mini-HDMI port that you can use to output 720p videos.  However, I read a rumor that Motorola might have locked the mini-HDMI port so that it only works when you are in gallery mode, which essentially mean you won’t be able to put your own movies or TV shows on the phone to watch on a bigger screen.  Take it with a grain of salt, I could not find any more information regarding this rumor, and I do not have my own mini-HDMI to HDMI cable to try it out yet.

    Back of the Phone: The speaker phone is loud, it should accommodate for all your speaker phone needs except in the most noisiest situations.  The camera quality is so-so, it is not at the quality of a point-and-shoot camera, but I mean, I really am not expecting a super nice quality camera on a phone.  The camera on the Droid X is capable of 8MP although by default, it is set to 6MP.  More MPs != better quality, I do not like how companies use the # of megapixels to advertise their products as if more = better.  It really does not matter how much megapixels your camera has if the quality of the camera sensor is a piece of crap. I took some pictures with the Droid X below and you can judge for yourself how decent the camera is.  The UI for the camera is OK, it tries to be slick and fancy, but most people just want to change some settings quickly and take the picture.  I really like the soft-felt-like-matte on the back, it provides enough grip but won’t cause the phone to be really annoying to take out of pockets.

    Battery Life: A seemingly common problem among android phones are their battery life.  On average, I believe that my Droid X can last one day on a full charge.  It is hard to judge right now because I just got this phone so I am always turning it on and using it very frequently so obviously I drain the battery faster than everyday common use.  Optimally, I would prefer my phone to last at least a day and a half.  I eagerly wait for the ability to {over | under}clock so that like my Droid, I can underclock when the phone is in sleep mode to conserve battery [it drastically increases your battery life when you underclock!].


    Android OS: I won’t go too much detail into the software aspect of the Droid X because the android OS is very dense in terms of all the different features and nuances that it has to offer and I won’t be able to sufficiently summarize it in one review.  But I must say that I absolutely love the flexibility of android, and the fact that I can think, “Hmm, I don’t really like the skin and widgets that Motorola designed for this phone, I wonder if I can change that.” and be able to actually do that.  I am not confined to only one way to how my phone looks like, or only one program that I am allowed to use to sync my device like iTunes.

    “Motoblur”: Motorola received a lot of negativity towards their custom skin, motoblur, in the past because it was very obtrusive and annoying.  For the Droid X, they made a major improvement in their skin [which they insist to not call it motoblur], but I personally still don’t like it.  First thing I did when I got the phone was download LauncherPro and customized my home screen the way I liked it.  However, for some people, they might actually like Motorola’s skin and widgets.  It’s up to you how you want your phone to look like.

    Processor: The Droid X comes with a OMAP3630 1GHz processor that makes this phone soooo smooth and slick.  Flicking between the different screens and switching between different applications is seamless.  This is very different from the Droid where sometimes I will sometimes see the phone stutter and freeze when I try to flick screens and open/close apps.  So far, the Droid X has never stuttered significantly and it never ceases to amaze me how fast apps are installed and how fast apps open on this beast of a phone.

    Swype: The phone comes pre-installed with Swype, which I absolutely love.  Swype is created by the same creator as the T9 texting format that we all know and love on our dumbphones.  He claims that this is the future of texting, and I think that it suits most people well.  I type so much faster with Swype now compared to if I was trying to hunt and peck for everything.  My decision to get a Droid X was partially because I realized that I can use soft keyboards with no problem thanks to Swype, so I do not need a physical keyboard like the Droid 2 that will be coming out in August.  That is good because the phone is not as bulky when there is no hardware keyboard.

    Crapware: One thing I don’t like is the pre-installed crapware that came with the phone.  Apps like Blockbuster, some EA racing game, and Backup Assistant are some of the apps that annoy me because you cannot uninstall them [besides the racing game demo], until this phone gets rooted.  I think pre-installed crapware is something that can tarnish a nice phone like the Droid X simply because they exist on the phone and they won’t allow you to easily uninstall it.  It is like buying a new HP laptop and seeing that it came pre-installed with a bunch of programs that you will never use.


    + Solid, well-built hardware.  It feels like a solid and refined product, and it does not feel cheap.  Motorola has done very well with the hardware-aspect of their Droid lineup so far.

    + Screen size, some may find it too big but for me, I think its great for reading and watching videos.  Pinch-and-zoom is excellent.

    + Smooth, slick and speedy UI experience because the Droid X sports the new generation of the OMAP processor.  The phone performs exceptionally well and when the 2.2 update comes out next month, it will only be even better, thanks to JIT.

    – Small volume rocker seems unintuitive since the size of the phone makes it hard enough to reach the rocker, it should be bigger to make it easier to feel and press.

    – Comes pre-installed with a handful of crapware that is not necessary and only serves to clog the apps list with applications and trial programs you’ll probably never use.

    – Battery life is not as good as it can be, but hopefully the ability to underclock will help the battery life.

    – Bootloader is encrypted and there is also an e-fuse chip that checks whether the firmware and kernel among other things is what Motorola designated.  If you try loading a custom ROM on the phone, the phone will not boot and it will need to have the stock ROM re-installed before you can boot.  Essentially, you cannot mod your phone and install custom ROMs on the Droid X.  Root will still be possible that will allow you to over/underclock, uninstall crapware and wifi tethering.

    Final Thoughts

    I recommend this smartphone for people who use a smartphone often to browse the internet and are heavy consumers of multimedia.  I am really hoping that android developers can do some exciting things with this phone although the chances of installing custom ROMS are zero to nilch.  Root should be inevitable, the potential for this phone is huge and I am excited for the future of Droid X.

    Motorola Droid X Video Camera

    Motorola Droid X Camera Pictures

    Filed under: Android,Reviews — Tags: , , , — Jesse Chen @ 10:07 PM


    Jesse is a software engineer at Facebook, who just graduated from UC Berkeley. Passionate about mobile technology and entrepreneurship, he started his own blog as a home for his tutorials, projects, and random thoughts. Follow him on Facebook to stay updated on his latest tutorials and projects.