You will find the card reader for the Aspire M3 481 listed below and other drivers for the Aspire M3 481 elsewhere on this website such as here. These drivers should work on both the 64bit as well as the 32bit operating systems. There are a number of other drivers listed on this website where you can find generic drivers which may or may not be more up to date. Note that the driver below is only for the card reader.
Check your hardware before you install the driver. There was only one version of the hardware in the Aspire M3-481. This card reader was from Realtek. This is a generic card reader which is widely used by computers. The driver for this Realtek card reader has been added down below. The internals read as:
Aspire M3-481 Card Reader