Also known as: embedded MultiMediaCard
eMMC (embedded MultiMediaCard) is a single package that combines flash memory and its controller, soldered directly onto a device’s board as built-in storage.1
Overview
Like an SD card, eMMC bundles NAND flash with a controller that handles wear leveling and presents a simple block device — but the package is permanently mounted rather than removable. The interface and command set are standardised by JEDEC. Because it is fixed in place, eMMC is reliable and compact, but capacities are modest and throughput sits below a modern NVMe SSD. It is common in phones, tablets, and the cheaper tiers of single-board computers.
Where it fits
eMMC is the middle ground between a removable SD card and a full SSD: faster and more durable than a typical card, cheaper and smaller than a discrete drive. Some single-board computers offer an eMMC module as a sturdier alternative to booting from microSD. For a GopherTrunk node that runs unattended near an antenna, soldered or socketed eMMC avoids the wear and connection issues that plague constantly written SD cards.
Sources
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MultiMediaCard — eMMC — Wikipedia, on embedded MMC flash storage and its JEDEC standardisation. ↩