The 128GB Memory Stick PRO Duo Using MicroSD Cards

📅 October 17, 2012
“Uh-oh! My memory stick ran out of space. Is 128 gigabytes possible?”

Yes, it is, and it is possible by combining two 64 GB microSDXC cards into a single 128 GB Memory Stick Pro Duo using a dual slot adapter. The result is a single Memory Stick Pro Duo with 128 GB of unformatted capacity.

The Parts

This technique involves two components:

The NEON MicroSD to Memory Stick PRO Duo Dual slot adapter accepts one or two microSD cards that are treated as one.

64 GB SanDisk Mobile Ultra microSDXC card with SD adapter. Different classes (speeds) are available, but class 6 is plenty fast for this project.

The microSDXC card works perfectly in the NEON microSD adapter even though the labeling on the adapter reads microSDHC. I had absolutely no troubles whatsoever, and both microSDXC cards read as a single 128 GB card.

Other microSDXC capacities are available. For example, two 32 GB cards will produce a single 64 GB Memory Stick Pro Duo card. In theory, any combination of microSD cards should work since the resulting capacity seems to add them together. For example, 32G + 16G = 48G. This was untested. After all, when using 128G, why go back?

Even single microSDXC cards will work. It is not necessary to use two cards with the adapter. Placing a single microSDXC card in slot 1 on the adapter will be seen as a single 64 GB Memory Stick Pro Duo.

Comparison of sizes and adapters.


This is easy. Just insert each microSD card into its own slot in the adapter. The card is ready to use.

Each microSD card occupies one slot in the adapter.


128GB Memory Stick PRO Duo constructed from two 64GB microSDXC cards.


Testing with a Single MicroSD Card

First, I used one card in slot 1 to find out what would happen. Only a few digital devices and Windows 7 recognized the card. This is because the 64 GB microSD card is preformatted with the exFAT file system that not all devices support. Ubuntu 10.10 did not recognize the card at all due to exFAT.

Windows 7 recognizes the single exFAT formatted card, but Ubuntu does not.

Notice the icon reads “SD”? In Windows 7, the card icon changes depending upon the adapter. Here, the microSD card was inserted using the bundled SD card adapter.

Windows 7 recognizes the card, but the only formatting options available from Windows Explorer are NTFS and exFAT. FAT32 is not given as an option.

Windows 7 Explorer only provides exFAT and NTFS as formatting options for the 64GB card.

The single 64G card is usable as-is, but the goal of this project is a full 128G card usable across many devices–especially those that only support FAT32.

Connecting to the Acer Aspire One 722 Netbook

The Aspire One 722 netbook does not accept the Memory Stick Pro Duo card by itself, but it does accept a regular Memory Stick. By placing the Memory Stick Pro Duo inside a Memory Stick adapter and then inserting that into the netbook, the netbook will read the card–but not in exFAT format.

The dual microSD card adapter fits inside a Memory Stick Duo adapter for compatibility with devices requiring it.


Memory Stick inserted in the Acer Aspire One 722 netbook.


Windows 7 icon using the microSD dual slot adapter.


MicroSD inserted in the Acer Aspire One 722 netbook using the SD adapter.

Windows 7 icon using the SD adapter.

The card must be formatted to another filesystem for compatibility with everyday devices.


To obtain 128G of space, both microSD cards must be inserted inside the dual slot adapter and formatted as a single unit. The cards are not formatted separately. Once fitted in the adapter, the device, computer, or OS will see the adapter as a single 128G memory card. Drivers are not required.

This provided a slight challenge since I needed FAT32. Windows 7 does not provide a direct option for formatting to FAT32. Ubuntu does, but it will not recognize the card in order to format it to FAT32 without the card first being formatted in FAT32. (Yes, yes. We could use the terminal, but let’s stick with a GUI for now.)

The solution? Use a PlayStation Portable (PSP)! After borrowing a PSP, inserting the card into the PSP and choosing to format the card, a fully operational FAT32 128G Memory Stick Pro Duo was available. Total format time on the PSP took about two seconds. Formatting was fast and simple.

Again, if using two microSD cards, both of them must be inserted and formatted as a single unit. The adapter handles the details.

Formatted Capacity

The total unformatted capacity is 128G. 64G + 64G = 128G. However, the usable capacity after formatting will be about 7% less. This means the 128G card will only provide about 118G of usable space.

Ubuntu, Windows 7, and the PSP all show 118G on a freshly formatted 128G Memory Stick Pro Duo.

Windows 7 FAT32 128G

Ubuntu 10.10 FAT32 128G

PlayStation Portable (PSP) FAT32 128G. MagicGate is unknown compared to official Memory Stick PRO Duo cards.


FAT32 and 128G

FAT32 works, and all 118G of free space is available for use. However, each individual file is still limited to a 4G file size limit. This is a limitation of the FAT32 filesystem, and not the 128G card.

PlayStation Portable (PSP)

The 128G arrangement using two 64G microSD cards is fully compatible with the PlayStation Portable game console to accommodate an almost endless supply of game save data.

PlayStation Portable XMB showing 118G free space on a 128G card.

There was no noticeable speed decrease, but entering the XMB main screen always caused about a three-second delay. Other than that, the 128G card functioned like any other Memory Stick Pro Duo without any slowdown or errors whatsoever.

MagicGate is not available with the 128G card.


Class 6 microSD cards were chosen instead of the faster class 10 cards because most devices tested were of low speed anyway. When used in cameras and other devices, all 128 gigabytes were fully recognized, and there was no noticeable lag.

When transferring files from Ubuntu to the 128G card, the transfer rate was about 6MB/s. Not the fastest, but more than plenty for its intended purpose as a large capacity backup card in a small physical card.


MicroSD cards are extremely versatile. Need a regular-sized 64GB SD card? Plug a microSD card into the SD adapter, and it will fit SD devices. Need a 64 GB Memory Stick Pro Duo? Just plug the same microSD card into a Pro Duo adapter, and Presto! Instead of purchasing different cards for different devices, the same card can be used with different (inexpensive) adapters.

I am positively happy with the results, and this has been a superb purchasing decision. Certainly, the price might be more than a dedicated USB hard drive of an equivalent capacity, but off-the-shelf USB hard drives do not fit inside consumer devices that only accept memory cards.

A 128G Memory Stick Pro Duo has many applications and provides plenty of space in a very small package. This is an easy way to add about 128G for ReadyBoost in Windows 7, for example. On top of that, the microSDXC cards can always be swapped into other adapters without needing to repurchase different cards.

Whether it be cameras, phones, or extra pocket storage, a 128G Memory Stick Pro Duo made from two 64G microSDXC cards is extremely convenient to have on hand.

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