eMMC stands for “embedded MultiMediaCard” and is a type of non-volatile storage device used in computing systems, including the Raspberry Pi Compute Module 4 (CM4). The Raspberry Pi CM4 features a built-in eMMC storage option in addition to the standard SD card slot. The eMMC storage is a flash memory technology that is soldered directly onto the CM4 module and offers a reliable and fast storage solution for embedded applications. Compared to SD cards, eMMC storage typically has faster read and write speeds, higher endurance, and more robust wear-leveling algorithms. It also eliminates the need for a separate SD card, which can be advantageous in space-constrained designs. The CM4 comes in different variations, some with eMMC storage and some without. The eMMC versions of the CM4 offer 8GB, 16GB, or 32GB of storage, depending on the model, and can be a good choice for applications that require reliable and fast on-board storage. The operating system is flashed to the eMMC. This is also where all control programs reside. Note: It is not necessary to flash the eMMC unless directed to do so by a Parallax Factory Authorized Support Specialist. This is typically done to reinstall the operating system, and to re install the parallax control engine.
