The firmware is specific to the model series- i.e., a 92 series firmware can't be used on a 62 series; a 62 series can't be used on a 64 series; etc.

The firmwares can be found on the sharp website. Just do a search for your model and add the word firmware on the end. Here's a link to the d64u firmware:
[Link: sharpusa.com]

CJ