ATCFWCHG.COM is a vintage DOS utility developed by SanDisk to convert CompactFlash (CF) cards from "Removable" to "Fixed" media, enabling them to boot on older IDE-based computers. The tool requires a native DOS environment and functions best with SanDisk Extreme cards connected as the Primary or Secondary Master. The utility can be downloaded from vogonsdrivers.com . Change old low HDD to a CF card? - HDD GURU FORUMS