FDS file format: Difference between revisions
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Rainwarrior (talk | contribs) m (link back to Famicom Disk System) |
Rainwarrior (talk | contribs) (cross correlation with FDS disk format) |
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* 4: Number of disk sides | * 4: Number of disk sides | ||
* 5-15: Zero filled | * 5-15: Zero filled | ||
The disk data follows the [[FDS disk format]], but gaps and CRCs are not included in the .FDS image. | |||
Note: Most games are an even number of sides. Ports from NROM were one side. No commercial FDS game had an odd number of sides greater than 1. | Note: Most games are an even number of sides. Ports from NROM were one side. No commercial FDS game had an odd number of sides greater than 1. | ||
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After the last file block, fill a side with all 0 so that exactly 65500 bytes is reached. | After the last file block, fill a side with all 0 so that exactly 65500 bytes is reached. | ||
Revision as of 21:54, 4 April 2019
fwNES was an NES emulator developed by Fan Wan Yang. Its most lasting contribution to the NES scene was its disk image file format, an image of the Quick Disk media.
The FDS format (file name suffix .fds) is a way to store Famicom Disk System disk data. It consists of the following sections, in order:
- Header (16 bytes)
- Disk data (65500 * x bytes)
The format of the header is as follows:
- 0-3: Constant $46 $44 $53 $1A ("FDS" followed by MS-DOS end-of-file)
- 4: Number of disk sides
- 5-15: Zero filled
The disk data follows the FDS disk format, but gaps and CRCs are not included in the .FDS image.
Note: Most games are an even number of sides. Ports from NROM were one side. No commercial FDS game had an odd number of sides greater than 1. Disk sides comes in the following order :
- Disc 1 Side A
- Disc 1 Side B
- Disc 2 Side A
- Disc 2 Side B
- etc...
After the last file block, fill a side with all 0 so that exactly 65500 bytes is reached.
