The four types at a glance
| Type | Contains | Interface | In this catalogue |
|---|---|---|---|
| eMMC | Storage only | Parallel, half duplex | 3,418 |
| UFS | Storage only | Serial, full duplex | 4,909 |
| eMCP | eMMC storage + LPDDR RAM | Parallel, half duplex | 6,434 |
| uMCP | UFS storage + LPDDR RAM | Serial, full duplex | 1,065 |
Two axes, really: eMMC or UFS decides the interface, and plain or MCP decides whether RAM is stacked in the same package.
eMMC — the older standard
eMMC (embedded MultiMediaCard) is managed NAND: flash memory plus a small controller in one package, presenting a simple block device to the SoC. The bus is parallel and half duplex, meaning it reads or writes at any moment, not both.
It has been the budget-phone standard for over a decade and is still shipping. Versions you will see marked include eMMC 4.41, 4.5, 5.0 and 5.1 — later versions are faster, but all are slow next to UFS. On a board, eMMC almost always means entry-level or older hardware, and in practice that correlates with lower capacity.
UFS — the current standard
UFS (Universal Flash Storage) replaced eMMC at the top of the market and has worked its way down. It uses a serial interface with a command queue and full-duplex transfer, so it can read and write at once. Real-world throughput is several times eMMC.
Versions run UFS 2.0, 2.1, 2.2, 3.1 and up. Anything you find marked UFS 3.x is flagship silicon. If a board carries UFS at all, it is worth checking the capacity carefully — this is the tier where storage is most likely to be 128GB and above.
eMCP and uMCP — the stacked packages
Phone boards have no space to spare. Stacking the storage and the LPDDR RAM into a single package saves board area and simplifies routing, so most mid-range designs use one.
eMCP = eMMC storage + LPDDR. uMCP = UFS storage + LPDDR. Together they account for 7,499 of the 16,776 parts here, which is why so many lookups return two capacity figures rather than one.
On a stacked part, both figures are binding. A replacement with the right storage but different LPDDR will not train memory at boot — the board will not come up. When you are sourcing an eMCP or uMCP, match storage and RAM.
Why capacity alone never picks a replacement
"128GB" is not a specification. To swap a part you need to match, in order:
- Interface family — eMMC and UFS are not pin-compatible, full stop.
- Ball-out — 153-ball, 221-ball, 254-ball and others are physically different footprints.
- Storage capacity — the obvious one.
- RAM capacity and LPDDR generation — on eMCP and uMCP parts only.
- Interface version — usually backwards compatible, but worth checking on marginal designs.
The IC checker returns all of these for a given part number, which is the practical way to work out what a donor board can actually supply.
Telling them apart from the part number
You generally cannot tell the type by looking at the package — they are all black rectangles.
The part number does encode it, but differently for each vendor. Samsung's KLM
prefix indicates eMMC while KM indicates a stacked MCP; SK hynix uses
H9 broadly across stacked parts. Full breakdown in
IC code marking schemes by brand.
In the general case, look it up. Guessing the interface family from the package outline is how boards get ruined.