Here is a little tutorial to setup two emunand on a single Sd for a 4.X 3DS. This setup could be useful for people that don’t own a gateway and want to have on the same SD: A MT emunand that you can update to last firmware to go online CFW as second emunand to run homebrew. For me it was an experiment and really don't know if it's worth to have two emunand on the same SD or if it's better to have two SD to swap when you need it. Warnings: If you never installed a CFW, don’t start from this tutorial. Too many things to do for a noob and I’m assuming you know all the problems involving a new CFW setup. Some steps aren’t very easy to understand for noobs, but the middle experienced member of this forum will complete all the steps easily. If you have problems ask some help. To have a dual emunand SD card, the two emunand shouldn’t be linked (at least one of the two has to be formatted, or created from a formatted Sysnand after creating the other), otherwise you can’t maintain the content for both emunand installed in the “Nintendo 3DS” folder (this obviously apply only if you already have a CFW with installed CIAS and don’t want to start again with a fresh install). IMPORTANT WARNING: improper use of BBcopy can damage data on your HD. Study how it works before playing with partitions. In this tutorial I’m using BBcopy from command line. The BAT files attached can be an help to understand BBcopy usage or to speed up its use after understanding how to configure its parameters. Using the BAT files without studying them a little bit can be very dangerous for your HD: the use of this files is on your own responsibility. Please don’t blame me if you lose important data. Objective and prerequisites Following this tutorial we are going to have a classic Gateway/MT emunand starting on sector 1 of your SD and the CFW emunand starting on sector 2097153 (= 0x00200001). To boot the CFW we will use a modified launcher. Instead of 1gb of unallocated space, your SD will need 2Gb of unallocated space, so it’s better to use at least a 8Gb SD. It’s better to start with an already working CFW. Probably you can inject a clean dump of your sysnand and then setup a CFW as usual, but I didn’t tried it. Let me know if it works. My OS is Windows 7, so I’ll describe how to setup the dual emunand under Windows. I expect that a linux user could easily replicate this tutorial with linux tools. Tools needed: Diskpart (it’s with your windows OS) BBcopy (Free and opensource port of linux dd – http://alter.org.ua/soft/win/bb_recover/ - you can find it in the zip file attached) Tutorial 1) Backup your CFW emunand running from a dos shell the command: bbcopy.exe bs=512 count=1953791 seek=1 ifd=1 of=cfwnand0.bin You have to run this command from the dir where is the BBcopy.exe file, and it will output the CFW NAND in file named cfwnand0.bin It will work in most cases without any changes, but it may need some customization for PC with more than a HD: ifd=1 means that the input disk to extract the emunand is disk 1, where disk 0 is always your primary HD. If you have only one HD and no removable disk other than the SD card with the emunand, your SD card will be disk 1. If you have more than one HD you have to guess the disk number of your SD and make some try with the above command. It’s no dangerous, so try and check if the output file is a valid NAND dump (e.g. you can check with an hex editor if the dumped file first sector looks like your sysnand backup). The parameter count=1953791 is for a Samsung NAND. For a Toshiba NAND use count=1931263. If you don’t know which NAND type you have, check the size of the NAND.bin backup made with the gateway or MT software:. · Toshiba NAND = 1931264 sectors = 988.807.168 bytes = 943 MB · Samsung NAND= 1953792 sectors= 1.000.341.504 bytes = 954 MB To make the backup simple, you can find some BAT file attached (to be placed in the same dir of BBCopy.exe). 2) Setup on the target Sd card your MT or Gateway emunand, or use one you already have. You will not loose data if you follow carefully the steps 3)Insert the SD with the emunand in your PC sd reader 4) Backup all the sd content (you don’t need to backup the emunand, but it’s better to do it; just in case you mess up your sd playing with partitions) 5) Open the command line and run diskpart 6) Use the command “list disk” to list your disks and locate the disk number of your SD. Check the disks size to locate the SD. Disk 0 should be your C: drive. I’ll assume the Sd is Disk 1 7)Type “Select Disk 1”. This select the SD disk. If your Sd has a different number, use it instead of the final “1” 8) Type “List Partition”. This command list all the disk the partitions and if you selected the right disk you’ll see only a partition marked as Primary and starting from offset 1024 Mb What we are going to do is deleting this partition and creating new partition starting from offset 2048 Mb, so to have enough unallocated space on the SD for two NAND images 9) Type “Select Partition 1” 10) Type “Delete Partition” 11) Type “Create Partition primary offset=2097152” 12) Type “List Partition”. If we did everything right, now we have a primary partition starting from offset 2040 MB. Otherwise jump again to step 10). 13) Type “format”. 14) Copy the backupped content of the SD on the card Now if you want you can test on the 3DS if your Mt emunand works properly. If you did everything right your emunand will work as always. Next phase is to inject the CFW emunand and load it with a tweaked loader 15) Inject the backup of your CFW on the SD starting from sector 2097153. From a dos shell use the command: bbcopy.exe bs=512 offs=2097153 ofd=1 if=cfwnand0.bin You have to run this command from the folder where are BBcopy.file and the previously created cfwnand0.bin WARNING: if you changed the ifd=1 parametere for dumping the CFW emunand, adjust the ofd=1 parameter accordingly. Beware that if you use the wrong disk number, you may loose some content on the destination disk. For this command too, attached to this tutorial there is a BAT file (that have to be placed in the same directory of BBcopy.exe and with the previously backupped CFW emunand). 16) Copy from the “Nintendo 3DS” folder on the SD with you original CFW setup to the “Nintendo 3DS” folder on the new dual emunand SD the folder with the system data. If you are a noob probably now you don’t know what to copy. I’ll give you a hint for the common case, but if you still don’t understand what to do, please ask some help on the forum If you have a MT emunand and a CFW emunand, unlinked with the sysnand, on both SD you have two subfolder in the Nintendo 3DS folder. One subfolder has the same name in both SD: it’s the folder with the data of your sysnand. Simply copy the other folder from your CFW SD to the MT SD. 17) Copy the CFW loader files on your SD root replacing boot.bin with the tweaked version in the zip file attached. 18) Rename the CFW launcher.dat in msetforboss.dat (or use the one in the attached zip). Now you can use the multiroploader.nds from your DS cart to select the emunand to launch with the usual DS profile exploit. DONE. Here is a little explaination of the tweak I did on boot bin: To redirect the sysnand to the SD the read/write functions are patched to be redirected to some custom code that change the device from firm to sdmc and simply add or subtract the sector offset to the nand phisical address to be read/write. The offset is a four byte value placed at position 0x14 in the file boot.bin (01 00 00 00 in little endian, that means 0x00000001 = 1 sector offset). Changing this value in 0x00200001 with an hex editor (I simply changed the value at 0x16 from 00 to 20) the loader will point to an emunand placed after the MT emunand starting from sector 0x00200001.