is it possible to read/write to my hard disk using hex codes?

Answer 1

Ah...not really. Hex is just a counting system, like Base10, which is the counting system that we're all familiar with. Hex numbers are values just like any other number, and there'd be no special significance to values written or read from a hard drive in Hex.

Some programs use Hex codes for the sake of more easily storing certain kinds of data, and those hex codes can occassionally be found stored in the program's config files...You can read and edit them using any hex editor...