Often stands for "Memory Card" and is used by older legacy emulators .
Prepare digital saves for use on real consoles via SD-card adapters like the The Preservation Perspective mcr to mcd converter
Because both formats contain the same raw binary data, "conversion" is often as simple as from .mcr to .mcd or vice versa. How the Story Unfolds (Usage Steps) Often stands for "Memory Card" and is used
Practical use cases
Pseudocode outline: