FDF Image

File Format
Name	FDF Image
Ontology	Electronic File Formats Disk Image Formats FDF Image
Extension(s)	.fdf
Released	1991

Overview

Floppy Disk File (FDF) are disk images used by the DOS software EZ-DisKlone Plus. Introduced in 1991, the format is a compressed disk image validated by a 16bit CRC.

File Identification

FDF files have the header "1A 46 44 46".

Specifications

The FDF file format is reverse engineered in 86Box, the source code can be found at:

86Box-master\src\floppy\fdd_img.c

Basically FDF used RLE compression.

if first byte is 0xFF then its end of block, if byte is 0x00 then remainder is stored uncompressed. Otherwise if b7 is set then the lower 7 bits are the repeat count and the next byte is the byte to repeat. If b7 is zero then its a store count, followed by the stored bytes.

Software

• Software download and Emulation

Sample File

• DOS Mouse Driver Image file

Links

• EZX's EZ-DisKlone™ Plus for DOS
• SSW/EZX's Super DiskCopy