Anex86 PC98 floppy image
From Just Solve the File Format Problem
(Difference between revisions)
(Created page with "{{FormatInfo | formattype = electronic | subcat = Disk Image Formats | extensions = {{fdi}} }} The FDI disk image format for NEC PC-98 disk images seems to or...") |
|||
Line 2: | Line 2: | ||
| formattype = electronic | | formattype = electronic | ||
| subcat = Disk Image Formats | | subcat = Disk Image Formats | ||
− | | extensions = {{fdi}} | + | | extensions = {{ext|fdi}} |
}} | }} | ||
Revision as of 00:25, 11 October 2018
The FDI disk image format for NEC PC-98 disk images seems to originate from the Anex86 PC98 emulator.
FDI File Header
The FDI header is 4096 bytes long, Intel little-endian, and starts with this 32-byte header.
typedef struct { BYTE dummy[4]; BYTE fddtype[4]; BYTE headersize[4]; BYTE fddsize[4]; BYTE sectorsize[4]; BYTE sectors[4]; BYTE surfaces[4]; BYTE cylinders[4]; } FDIHDR;
The next 4,064 bytes of the header seem to always be pad bytes.
FDI file image contents
The remaining portion of the file is a raw dd-style image of the disk. In the case of an HDM image, you can prepend a 4096-byte header onto the image to turn it into an FDI (see example below).
Examples
For a 1261568-byte "2HD" disk image (like *.HDM format), the header is as follows:
Field | Value | Comment |
---|---|---|
dummy | 0 | |
fddtype | 144 | Unsure what this value actually means |
header size | 4096 | Includes the 32-bytes in the header |
fdd size | 1261568 | |
sector size | 1024 | |
sector count | 8 | |
surfaces | 2 | double-sided disk |
cylinders | 77 |