I have a late 2012 MacBook Pro and I've always had this problem with storage. Sure, 128 GB is definitely enough, but having a Windows 10 partition at the same time completely reduces the amount of storage required for normal day to day usage for me. I found a solution where I would have an external MicroSD card with an adapter that fits in flush within the SD card slot so that it's portable as if it was never there. Although I'm aware that an SD card would slow things down, I still would like to boot Windows off of the 128 GB MicroSD card. After searching around the internet for a while, I still haven't found a way to do it. Here is what I have so far:

• A Windows 10 ISO image
• A working VM of Windows 10 (will be deleted later)
• Using a program called WintoUSB, the entire VM to my SD card
• A .dmg file of the SD card contents

The SD card I have does contain the full suite of the required Windows drivers. I haven't tried because I haven't been able to yet, but from the given information, all I need to know at the moment is how to boot from the SD card. If it is required, I am OK with reinstalling any software or doing any steps over again.

3 Answers

This is because Boot Camp Assistant won't work with any external storage devices. It's been clearly stated on the Apple website about using Boot Camp:

Can I use an SD, SDHC, or SDXC card to install Windows on my Mac?

No. You can’t use SD, SDHC, or SDXC cards with Boot Camp to install Windows software on Mac computers.

The only option you got is Parallels Desktop. Because—as you mentioned—it's the best cross platform so far and you don't need any drivers at all (This means basic drivers such as audio and display).

After format your SD card as Mac OS Extended (Journaled), you can easily choose the SD card as the installation disk and the parallel desktop will look after the rest.

I do not have the reputation to comment, so I'll answer here

Make sure that your SD card is formatted to a Mac OS journal, when this is done, make a partition in bootcamp, where you can make a windows partition on this new formatted SD card.

Hope it helped, cheers!

It is possible to boot windows10 from MacBookPRo(2012 or later models). The MacbokPro has the built in SD card slot and when the startup chime rings hold on the option button to reveal the bootable options. It will certainly show the SD card as bootable if it is. I used WintoUSB to install Win10 Pro edition x64 onto the SDCard. SDXC UHS-1 card. Make sure you do it in GPT and UEFI and also legacy as installation mode. once this will take about 40min to install and the you can use the same card in the MBP slot and boot. Now what I am rying to do is that.. instead of SDXC card I am using a microSD card in the SD adapter. I installed win10 as described above and then ussing it . In the mac wiht i select the sd card as boot device it is showing win10 logo and after some time showing blue screen with error msg .. INACCESSIBLE BOOT DRIVE..