marked141 wrote:
I always thought, from piecing together different information, that an SD card is basically a chip in a plastic housing with the bare minimum of circuitry to the interface.
Completely correct.
Up to a few years ago memory cards had a minimum of two chips. One for storage and the peripheral interface controller. With the 8, 6, 5, and 4um interface we have gotten down to a single chip.
Even uSD and mSD cards with a single “chip” they are actually a multi chip carrier (MCC) which puts two chips into a single form.
Today Samsung has managed to put it all into a single “chip” which.
To over simplify
Keep n mind solid state storage is nothing more than the equivalent of a capacitor collection or battery pack.
Binary data is stored as charged cells and non-charged cells.
If you were to open a micro SD card, removing the plastic, you find a chip on PCB. But, go further and crack that chip open horizontally, you’ll see two distinct regions. The larger one is storage; the smaller the controller.
That controller, can be one of two types. A hardware control actually uses something beyond the serial bus to handle the storage. Often with encryption and levelling.
A software controller tells the computing device: I’m serial access storage! Feel free to abuse me since I’m just a dumb floppy.
Most usb sticks use the MSD command and nothing more. A microSD has more instructions in the controller than the early CPUs did.