One of the nice things to come out of Microsoft’s complete overhaul of the Windows installer for Vista and beyond was that it did away with the idea that different variations of Windows needed different discs. Previously each distribution of XP (Home/Pro/MCE) required its own disc, and then each license type (OEM/Retail/VLK) also required its own disc. This lead to an astounding number of disc types, and complete and utter frustration when for users attempting to install Windows and not having the correct disc to go with the key they had.
With Vista’s image based installer, we saw Microsoft consolidate all of this – one disc could contain every distribution of Windows, allowing a user to always be able to install Windows with any Windows disc, regardless of what their key was. This greatly simplified the installation process, resolving one of the most frustrating things about installing Windows XP.
So imagine our surprise when we’re taking a look at our TechNet copies of Windows 7 and find that there’s a different installation disc for each distribution of Windows. With the version of the Windows installer that comes with Win7, there is a new file at /Sources/ei.cfg that tells the Windows installer what OS it should install. Here’s what the file looks like from the ultimate disc:


When the Windows installer sees this file, it becomes keyed to whatever distribution the file specifies. In this case with an Ultimate disc, we cannot install Home Premium or Professional. We have not yet had a chance to test OEM and retail keys since we don’t have both, however it certainly looks like the installer is going to make a distinction there too.
Perhaps the most interesting bit of this is that the installation process itself hasn’t changed – the Windows installer still supports One Disc to Rule Them All operation, and the Windows image that comes with Ultimate for example has absolutely no problem installing lesser versions. In fact if you remove ei.cfg so that the Windows installer is not told to install a specific version, it will revert to One Disc mode. The distinction between discs is entirely trivial, dictated by a single 51 byte configuration file. You can have a One Disc installer, Microsoft just don’t want it to be the default action for some reason.
Now to be fair, this didn’t entirely catch us off-guard. We first saw this file and its functionality with the Win7 Beta, but until now we did not know if this was something that was specific to the testing versions of Win7, or if it was going to be pushed out in to retail with this limitation. Now we know our answer.
The biggest downer though is that this file is fairly tricky to remove. For copies of Windows packed in ISO files or burnt to discs, this requires remastering the ISO/disc in order to maintain its bootability – it’s not possible to just copy the contents to a new file/disc sans ei.cfg and have a One Disc. Building a proper bootable ISO/disc is still more of a dark art than a science. Users looking to install Windows from a USB flash drive will have an easier time – since installers set up on those types of drives are rewritable it’s easy to remove the offending file. Though this may not be the case with officially distributed flash drives should Microsoft go ahead and distribute Win7 that way, as rumors suggest they will.
In any case this is a significantly disappointing action coming from Microsoft. The One Disc returned the sanity to installing Windows, and made having so many distributions more bearable. Now as far as pressed media is concerned, we’re back to the dark ages of Windows XP (I guess Microsoft really was trying to copy everything about XP?). Geeks would be well advised to burn a copy of Windows 7 with One Disc capabilities as soon as they have it – if the experience is anything like Vista then the benefits will quickly make themselves apparent.
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  • straubs - Friday, August 7, 2009 - link

    Please stop apologizing for Microsoft taking a backwards step here. What exactly is gained by making anyone have to jump through this unnecessary hoop?

    You could argue that anyone upgrading a Windows OS instead of buying a new computer is already somewhat of a tech-literate person and shouldn't get confused by the simple option of choosing which edition to install.
  • Casper42 - Friday, August 7, 2009 - link

    I wouldn't make that argument at all.

    I think they are doing it the right way when it comes to COTS.

    For a Retail Product that comes boxed and as was said earlier, the user is expecting a certain version, why not just install that version?

    I would expect however that MS would omit the file for MSDN/Technet ISO downloads because those are the truly technical people who know how to pick what version they want.

    @RYAN - Can you use a Windows 7 "One Disc" and check the install sequence of CD Key vs Version prompt?
    In other words, are you prompted for the key first still?
    And then if so, enter your Key for your Ultimate version and see if you are still prompted for which version or not.

    The other interesting test would be to grab a Vista OneDisc and ADD the file mentioned in the post and see if it has any effect.
  • erple2 - Friday, August 7, 2009 - link

    Perhaps what they should have done instead was still pop up the installer picker, but have the default set to whatever the disk was intended to ship with. That way, the tech savvy can now pick the appropriate install.

    Or, enter the key first, and let the key then determine which one is the appropriate version to install (assuming that's how the keys work).
  • CSMR - Saturday, August 8, 2009 - link

    Yes, that would make the most sense.
  • eggythetech - Friday, August 7, 2009 - link

    Thought this might interest you the File sizes of the 32bit and the 64Bit win7 download from MS Volume Licensing. I don't know Why the sizes are different for the 64bit.

    SW DVD5 Win Pro 7 32BIT English Full MLF X15-71033 2289 MB ISO
    SW DVD5 Win Pro 7 32BIT English Upg MLF X15-73572 2289 MB ISO

    SW DVD5 Win Pro 7 64BIT English Full MLF X15-71037 2976 MB ISO
    SW DVD5 Win Pro 7 64BIT English Upg MLF X15-73888 2975 MB ISO
  • solidsnake1298 - Friday, August 7, 2009 - link

    64bit system dll's are significantly larger than 32bit dll's. That is why the system requirements for 64bit versions of Windows Vista and 7 are higher in the memory department. For Windows 7, the minimum memory requirement is 1GB for the 32bit version and 2GB for the 64bit version. The same applies for hard drive space. 32bit Windows 7 requires 16GB while the 64bit version requires 20GB.
  • Casper42 - Friday, August 7, 2009 - link

    Great explanation, except you missed the point.

    Looking at JUST the 64bit installers, one of them is 1MB bigger than the other.

    However looking at JUST the 32bit ones, they are the same size.
  • HollyDOL - Saturday, August 8, 2009 - link

    Well, they don't have to be same size. Don't forget the size of MB is 1,048,576 Bytes... using rounding you can easily hide 400kB file...

    let's say full 32 bit version is 2289.4 MB
    upgrade 32 bit version is 2289.1 MB
    ... rounded to MB... both are 2289MB

    now 64bit version
    full... 2975.6 MB
    retail... 2975.3 MB
    rounded and you get full having 2976 and retail 2975MB.

    Unless we know the size in Bytes there is no way telling whether 64bit version is in this point of view any different from 32bit.
  • jsedlak - Friday, August 7, 2009 - link

    How else would the disc know what version you were installing?

    Perhaps they are using it to easily remove the confusion of a "Select version" screen. Although they could probably have users enter the key and then give them a list of options with the highest possible being default selected.
  • Griswold - Saturday, August 8, 2009 - link

    The disc doesnt need to know. The license key should determine the version. Vista has been doing it and it works fine, why change it again?

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