The original tutorial in French can be found at http://ironseb.free.fr/a320/Dualboot/installation/. This is merely a translation, and all credits for writing the original tutorial go to Ironic. Minor edits have been made by me to improve readability or ease of use. Please note that the screenshots are in French, as taken from the original tutorial. This translation may or may not be accurate, and I am not responsible for any damage to your Dingoo A320 that follows from using this tutorial. Thanks for your understanding :)

Dual Boot on the Dingoo A320 (ILI9325 and ILI9331)

This tutorial is aimed at users of Windows XP 32-bit. It explains how to install the dualboot loader on your Dingoo A320. It also covers the actual installation of Dingux, since that consists of no more than a copy and paste of the Dingux files. Thanks to Yoannd26 for the screenshots. Many people want to install dualboot in order to be able to run Dingux. The installation of the dualboot loader seems to be very hard, while it can actually be very easy. Several tutorials exist, and several forums are filled with information on this. I think too many tutorials exist for this, and a new tutorial containing all information in one place is needed.

Downloads

You will need these files to install dualboot.
usbtool Drivers
Dualboot Loader

Several start packs exist, you can just pick one and see if it does what you want it to:
DinguXMB Starter Pack
Toddler's Local Pack (very comprehensive)
Warpedflash's Local Pack (very comprehensive)

What is dualboot?

Without going into technical details, dualboot allows, as its name implies, to choose between two different operating systems when the device is started. Booboo is the Spanish software engineer who made the dualboot loader for the Dingoo A320.
By default, the Dingoo can only boot one operating system: the original firmware. After installation of the dualboot loader, you can press SELECT when you boot the device to run Dingux instead of the original firmware.
Installing dualboot is completely safe (it's not possible to brick your Dingoo) as long as your battery is full enough.
Note: Be sure to FULLY charge your Dingoo before attempting this tutorial! Installing dualboot does not alter the usage of the Dingoo, except for allowing another operating system to be run as well. It's still perfectly possible to run the original operating system. For installing dualboot, you do not need a MiniSD card (however you do need it when you want to try to run Dingux). It's recommended to take your card out when installing dualboot, and backing up the internal memory of your Dingoo in case something goes wrong (there's a first for everything, and better safe than sorry).
When dualboot is installed, you will see a Dingux logo when you boot the device. If you try to press SELECT without a MiniSD card, or without installing Dingux, the Dingoo will freeze on the Dingux screen and you will need to use a toothpick or thin object to reset your unit.

What is Dingux?

Dingux is the name of the Dingoo-version of Linux. Booboo has developed Dingux, based on the original Linux core. It's very easy to install Dingux, it's a matter of simply copying and pasting a bunch of files. Get a starter pack (links can be found at the top of this tutorial) and simply extract the archive to your MiniSD card.

Installing dualboot

There are several methods to install dualboot. In this tutorial, we will use usbtool. There are versions for Windows XP, Mac OSX, and Linux.
When this software is put in memory and executed, it will flash a small part of the Dingoo memory, the so-called NAND Flash (the location in the internal memory where the original firmware is stored). The dualboot loader is placed just before the original firmware. When the Dingoo boots, it checks if you are pressing SELECT. If you do, it loads Dingux. If you don't, it will continue to start the original firmware.
Unlike flashing the firmware (where the computer actually does the flashing and a USB cable or other failure could brick the dingoo), the dualboot installer lets the Dingoo itself write in his own memory. Because the single second it needs to place the flashing program on the Dingoo is very short (one second to be exact, hehehe) there is very little chance that anything goes wrong.
Even though it's very unlikely that you will brick your Dingoo while installing dualboot, it might still happen. In that case, you can simply use the unbricker tool to restore your firmware (the dualboot will stay intact when using the unbricker tool). The only chance that you REALLY brick your Dingoo is when the unbricker tool doesn't work (which is very unlikely, but everything is possible!).

Though this might all sound very complicated, it's actually very simple to install dualboot. First you will need to find out the version number of the LCD controller. Currently only the versions ILI9325 and ILI9331 are being used in the Dingoo A320. To check it, do the following:
* Turn on your Dingoo
* Go to Options -> About
* Using your D-pad (arrow keys), enter the following: UP, RIGHT, DOWN, UP, RIGHT, DOWN
A hidden screen with black text on a white background will now appear, stating your LCD controller version. Look for the line LCD MODULE and note the version number. Note: When you stay in the hidden screen for too long, your Dingoo will freeze. Simply reset it with a toothpick or other thin object. Now you know the version of your LCD controller. You'll need to start your Dingoo in boot mode in order to flash it. Find a toothpick or other thin object, and reset your Dingoo while you're holding B. The screen will stay blank. To check if it's in boot mode, try to turn it on. If it doesn't work, that means the device is in boot mode. Note: If you want to stop installing dualboot and just turn it on like you normally do, simply reset the Dingoo to get it out of boot mode. * Download the usbtool drivers and unpack it on the desktop.
* Download the dualboot installer and unpack it on the desktop as well.
* Connect the Dingoo to your PC. Note: If you have already installed boot mode drivers before (for example, when running the ChinaChip booting tool to flash your firmware), be sure to uninstall these first. As soon as you connect your Dingoo to your PC, it will recognize it and ask you what drivers to install. Choose "Install from a list or specific location". Uncheck "Search removable media" and check "Search in this location" Click browse and select the jz4740_usbtool_drivers folder on your Desktop. Click OK. Click Next and the driver will be installed. If it's done, you can click "Finish". Now the driver is installed. Let's check if it's really there. Right-click the My Computer icon (either on your desktop or in your Start Menu) and click "Properties". In the Properties window, go to "Hardware" and open the Device Manager. Under LibUSB-Win32 Devices, you will see Jz4740 USB Boot Device (Rockbox USBtool). This means the driver is installed successfully. Now open the dual_boot_installer_20090813 folder on your Desktop. You will see two different .bat files, one for each LCD controller version. Choose the one that corresponds with the LCD controller in your Dingoo. You will see a command line window for a few seconds, just let it do its job. The screen of your Dingoo should now light up and show a dual boot flasher. Note: If you don't see the screen of your Dingoo light up after these steps, be sure to uninstall any ChinaChip drivers showing up. If this does not work, try using Safely Remove Hardware to "unplug" your Dingoo, take out the USB cable, reboot in boot mode, and plug it in again. If that STILL does not work, try installing a newer version of the original firmware. Now press START two times to continue to the confirmation screen. Select YES to continue. Press START, START, and select YES. Now the dualboot will be installed and the device will restart after you press START again. Congratulations! You just installed dualboot on your Dingoo :)