I recently purchased a new Toshiba L300 laptop computer running Windows Vista. Since I prefer Windows XP, and have a spare copy of the software, I attempted to replace Windows Vista with Windows XP. I proceeded through the standard steps to install Windows XP – booting from the Windows XP CD into the setup. However, when the screen appeared asking on which partition Windows should be installed all that it said was “Unknown Disk” and it was not possible to proceed beyond this point. My research into the problem indicates that Windows XP does not have the drivers for the new types of hard disk. The disk properties are: “Intel(R) 82801 HEM/HBM SATA AHCI controller” and “Intel(R) ICH8M Ultra ATA Storage Controllers – 2850”. As far as I am aware, I will need to install the drivers for the drive (f6flpy3289.zip) at the F6 prompt during the installation loading sequence, which allows for the installation of third party drivers. Are you able to advise whether I am on the correct track and whether I could expect any other problems installing Windows XP on this laptop?

In many cases, new computers are designed and configured for a particular minimum version of Windows. In the case of the Toshiba L300 laptop that you purchased, the minimum supported version of Windows is Vista. The computers generally have this constraint because they usually want to provide the latest and greatest operating system while also having the most recent hardware to take advantage of all the new features and optimisations present in the latest release of the operating system. However as you have found, this new hardware often requires dependencies found in the newer operating systems and thus difficulties can arise when attempting to install an old operating system on the computer. The “Unknown Disk” message that appears when you reach the partitioning screen in the Windows XP setup could indicate two possible situations. The first is as you outlined – Windows does not have the drivers for the hard drive controller, and thus cannot access the drive. The second is that the drive could be corrupt or faulty. Given that you have previously been able to run Windows Vista successfully on the computer I doubt that the drive is faulty, otherwise you would have likely experienced problems running Windows Vista. However, if you are unsure then you could always try to reinstall Windows Vista on the computer and check whether the drive appears during the Windows Vista setup wizard. If the drive does not appear and a similar problem arises with just “Unknown Disk” being displayed, then it does seem there is an issue with the drive. In this case you should contact the computer manufacturer for assistance, as they may need to replace the physical hard drive in the computer. Fortunately since your computer is a brand-name machine and relatively new it may still be under warranty making the replacement process a bit easier. In the more likely situation that you find the drive does recognise correctly during the Windows Vista setup then the problem is most likely related to Windows XP not having the correct hard drive controller drivers.

Doing some research on the internet it seems that this problem is quite well known, and fortunately there are two ways around the issue. By way of background, newer computers with Intel chipsets come with a feature called Advanced Host Controller Interface (AHCI) which may look familiar from the disk properties that you mentioned in your question. AHCI is a method for the computer to communicate with hard drives connected via Serial ATA (SATA) which is the most common method for internal hard drives to be connected to a motherboard on a modern computer. However, only Windows Vista (and later) systems support this new AHCI feature out of the box, which explains why Windows XP is unable to detect the hard drive. The first method to get around this issue is what you described in your question – download the AHCI drivers and then load them when the F6 prompt appears in the Windows XP setup. Looking through the Toshiba website I could not find any SATA AHCI drivers for your specific computer, although when I searched for the file name that you provided (f6flpy3289.zip) in Google it returned the Intel website which does provide this file. From reading the description of the file it seems like it should work for our purpose, although the only way to know for sure would be to try using those drivers. This will bring you to the next challenge, since you need some way to load those drivers during the Windows XP setup. The setup requires you to use a floppy disk for the drivers and most new computers do not come with a floppy drive since they are old technology and not used to a great extent. In the situation that the computer does not have a floppy drive you will need to acquire a USB floppy drive which you can connect to the computer. In the first instance you will need to use the USB floppy drive to copy the extracted driver download onto a floppy disk. Then, you can use the floppy drive during the Windows XP setup to load those drivers. Be aware, there is a possibility that the Windows XP setup will not recognise the USB floppy drive. Should this occur, it might be because the BIOS setup on the computer has not enabled USB floppy drive support (or a similar setting). The BIOS setup is the basic computer configuration stored on the motherboard of the computer. This provides sufficient information and configuration for the computer to boot before it hands control over to the operating system. The BIOS also manages the essential hardware devices on the computer to ensure that they are all in proper working order. As each computer BIOS is different I cannot provide specific instructions about the setting(s) which you may need to check and change, but most modern computer BIOS’s are fairly user friendly so you should be able to find the setting. However, be aware that changing the wrong setting in the BIOS could have other ramifications for your computer, so proceed with caution. If you are unsure about anything then I would suggest that you speak with your computer manufacturer for further advice before changing anything. Nevertheless, once the drivers have been loaded during the Windows setup it should recognise the hard drive and allow you to continue with the installation of Windows XP.

There is also another workaround for the problem, although it is not as neat as the previous solution (loading the drivers during the Windows XP setup) and I would only recommend that you use this workaround if you are unable to find the necessary drivers for Windows XP. As we previously discussed, Windows XP does not support SATA AHCI without additional drivers. It is possible to set the hard drive controller to compatibility mode so that it can be used with older operating systems that lack native support for SATA AHCI. However, this does mean that you will not be able to take advantage of the features offered by SATA AHCI. That said, many users report that the advantages are not that great for a standard, non-performance seeking user and you most likely would not notice any difference. To enable compatibility mode for the computer, go into the BIOS setup when the computer first starts-up. A message should appear saying “Press F2 to enter setup” (or similar) and tapping the required key should open the BIOS setup. When you are in the BIOS setup, go to the section with the SATA setting and change the mode from AHCI to Compatibility. Once you are done close and save the BIOS setup and then restart your compute to boot from the Windows CD and enter the Windows setup. Your hard drive should now be recognised and you can proceed with the installation of Windows. Of course, make sure you heed the warning that I previously mentioned about the BIOS setup (whereby changing the wrong BIOS setting can have unintended side-effects) so make sure that you understand what you are doing and if you are unsure seek advice from the computer manufacturer.

Once Windows XP has finished installing you may be tempted to change the SATA setting back to AHCI. However, be aware that this will not work and if you do change the setting back to AHCI it will result in Windows XP no longer booting (and will likely instead cause a blue screen crash). This is because when you changed the SATA mode to Compatibility that essentially disabled the AHCI functionality, removing the need for a driver to be installed. In other words, both the hard drive controller and the operating system are speaking the same language. If you subsequently change the SATA mode back to AHCI you are essentially changing the language of communication between the hard drive controller and the operating system, and because Windows XP does not understand the new language (with the necessary driver, or translator to continue our analogy) they can no longer communicate. If you do wish to change to AHCI down the track there are ways to make this happen, involving installing the AHCI driver within Windows and following a particular procedure for the switch-across (and you are welcome to contact me again for further advice on this aspect if needed). However, if you did want to do this in the future then the most straight-forward method would be just a clean reinstallation of Windows XP and include the AHCI drivers when prompted during the Windows XP setup.

Assuming that Windows XP has now been successfully installed on your computer you will need to move your focus towards installing the required device drivers on the computer. Since the computer shipped with Windows Vista, it is likely that Windows XP drivers did not come with the computer, so instead they will need to be downloaded. In the best case scenario, if you search for your computer on the Toshiba website, hopefully Windows XP drivers are provided which you can download. Failing this, you may need to identify the manufacturer and model of each component in the computer (e.g. graphics card, sound card, network card, etc.) and then download the Windows XP drivers from the website of the manufacturer for each item. You should be able to get the required information about each item from the documentation that came with your computer (as usually they have a listing of all components in the computer). If you use this method, make sure that you do download and install the correct drivers from the legitimate source (i.e. the manufacturer’s website) as incorrect drivers can be known to cause system instability and other issues.