MultiMediaCard (MMC)
Memory Cards · 7 specs
Direct Answer
MultiMediaCard (MMC) is a solid-state memory card standard introduced in 1997 by Siemens and SanDisk based on a 7-pin serial bus. Evolving into RS-MMC and MMCmobile, it formed the physical and protocol foundation of both the SD card and JEDEC eMMC (embedded MultiMediaCard), the ubiquitous internal storage standard for mobile devices, smart TVs, and single-board computers.
Source: MultiMediaCard Association (MMCA) / JEDEC Solid State Technology Association (JESD84) · Last reviewed Aug 28, 2026
Specs
| Governing Standards Bodies | MMCA (historically) / JEDEC (eMMC Standard JESD84-B51A) |
| Introduction Year | 1997 (Siemens & SanDisk) |
| Physical Dimensions (Full MMC) | 32.0 mm × 24.0 mm × 1.4 mm (7-pin interface) |
| Reduced Size Formats | RS-MMC (24.0 × 18.0 × 1.4 mm), MMCmobile (dual voltage), MMCmicro (14.0 × 12.0 × 1.1 mm) |
| Embedded Evolution | eMMC (eMMC 4.5, 5.0, 5.1 delivering up to 400 MB/s via 8-bit parallel bus in BGA packaging) |
| Bus Widths | 1-bit (legacy MMC), 4-bit (MMC Plus), 8-bit (eMMC HS400) |
| Operating Voltages | 3.3V (standard) / 1.8V (dual voltage / eMMC) |
The Predecessor to Secure Digital
MMC was the direct precursor to the modern SD card. Full-size MMC cards share the exact 32 × 24 mm length and width of SD cards but are noticeably thinner (1.4 mm vs 2.1 mm) and feature 7 surface pins instead of 9. Because SD slots were intentionally engineered with backward compatibility, almost all legacy SD card readers and cameras can read and write standard MMC cards.
eMMC: Transition to Embedded System Storage
While removable MMC cards were eclipsed by SD cards in retail markets, the JEDEC Solid State Technology Association standardized the underlying protocol as eMMC (embedded MultiMediaCard). Integrated into a single BGA chip containing NAND flash and an internal controller, eMMC 5.1 (HS400 mode) delivers up to 400 MB/s over an 8-bit parallel bus, serving as the primary cost-effective internal storage medium for billions of budget smartphones, Chromebooks, smart TVs, and IoT gateways (e.g. Raspberry Pi Compute Module).