FIELD GUIDESource-led reference
Port & Cable

Two separate evidence layers

SD card form vs capacity and bus labels

Keep full-size SD and microSD physical form separate from capacity classes and bus-interface terminology.

Question this page answers

Does the card size tell me the SD capacity class, bus generation or exact reader support?

No. Use the physical connector records to identify the form, then verify the implementation on the exact device, cable, adapter or system documentation.

Physical connector layer

Full-size SD card formSD and microSD are distinct physical card forms. The form-factor label does not by itself establish capacity class, bus mode or recording performance.microSD card formThe SD Association treats microSD as a separate, smaller form factor from full-size SD. Capacity, bus interface and speed-class support remain additional distinctions.

Technology / standard layer represented in the atlas

SD capacity classes: SD, SDHC, SDXC and SDUCThe SD Association defines SD up to 2 GB, SDHC above 2 GB through 32 GB, SDXC above 32 GB through 2 TB, and SDUC above 2 TB through 128 TB. These are capacity families, not speed ratings.UHS-I and UHS-II bus interfacesThe SD Association lists UHS-I SDR104 at 104 MB/s and UHS-II at 156 MB/s full duplex or 312 MB/s half duplex. These bus figures are not guaranteed sustained card-write rates.SD Express interface overviewSD Express introduces PCIe and NVMe operation in the SD ecosystem. The SD Association distinguishes host implementations; a PCIe-only implementation must not be assumed to accept ordinary SD-mode cards.

Related permanent comparisons

SD versus microSDCompare physical card forms; verify capacity, bus and speed class separately.SD capacity versus bus interfaceCapacity family and transport technology are different layers.
Browse represented media pathsOpen Topology Studio
Discovery is not a compatibility verdict.

These discovery surfaces route and reorganize facts already represented in the atlas. They do not add electrical ratings, universal pinouts, measured tolerances, exact-device support, wiring approval or an end-to-end compatibility result.