The O2Micro MemoryCardBus Accelerator driver is a software component used to enable the functionality of a MemoryCardBus device on a Windows computer. MemoryCardBus is a type of interface used for connecting memory cards (such as SD cards or CompactFlash) via a CardBus slot, which is typically a type of expansion slot on older laptops. O2Micro is a company that produces hardware controllers for these types of memory card interfaces, and the driver is necessary for the operating system to recognize and interact with the device.

The O2Micro MemoryCardBus Accelerator driver allows Windows to properly detect and manage the device, ensuring that memory cards can be read, written to, and used with your computer through the CardBus slot.