I use a 64 GB Class 10+ microSD card with the computers' built-in card reader (sometimes requires a microSD to SD adapter), in place of a pen drive. This allows me to connect the card to devices without available USB ports.

Are microSD cards the same "under the hood" as a USB pen drive, or are there any advantages or disadvantages of using it compared to using a USB pen drive?

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3 Answers

Are microSD cards essentially the same inside the shell as a flash drive?

SD cards have their own communication standard and command set. A microcontroller in the SD card implements these, with possibly hackable firmware and vendor-specific commands.

A flash drive will implement the USB mass storage protocol in a microcontroller instead. These also have firmware that can be hacked/flashed/changed but aren't implementing the same standard as SD cards.

Both USB and SD cards have a similar internal overall architecture (not internal architecture - you can't hack a USB microcontroller to work as an SD card microcontroller, for example), but different external interface and different protocols.

There's no practical difference from an end-user standpoint other than:

• SD cards are typically smaller (esp. microSD),
• full-size SD cards have a write-protect slider,
• USB 3.0 is faster than the latest SD card protocol but I believe no flash hardware can approach the max speed of USB 3.0.

On the hardware side ...

• The USB protocol requires more software support (due to enumeration, etc.) than the SD protocol. This doesn't matter these days with powerful embedded CPUs being available for all sorts of portable devices and the prevalence of smartphones.
• Early SD card protocols were simple and cheap to implement in hardware, and you could even hack an SD card reader into an old Linksys router without hardware SD card support. (you couldn't do that with USB unless the chipset supported it).

Assuming you mean advantages over standard USB jump drives, there is no major dis/advantage seeing as how they are, more or less, the same technology. The only caveat is read/write speed. However, the same argument can be said for both.

Also assuming that you connect your Micro SD's using either a SD Card card adapter (computers) or Micro USB to Micro SD (tablets/phones), you can make sure that the cable/adapter/port are of the same speed class. See the following for more information: SD Card Speed Class

Very few USB "flash-drives" have the feature on every standard SD card and microSD to SD holder: a READ ONLY switch. Whenever I use someone else's machine, I ALWAYS put the SD's mechanical switch into Read Only.

As for "speed" (and my USB-3 adapters to U3-Standard cards aren't "slow") security seems more important when I consider ... "BAD USB", which has NOT gone away. Many certified devices are vulnerable to this. How fast can YOUR USB "flash-drive" infect your network and compromise ALL your personal data? "Convenience is the opposite of security (and privacy)."

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