Example: chdman -c lzma,flac = LZMA for data, FLAC for audio. | Media Type | CHD size (raw → compressed) | Example | |------------|-----------------------------|---------| | Hard disk (CHD-HD) | 50–90% | chihiro , naomi hard drives | | CD-ROM (CHD-CD) | 30–70% | PlayStation, PC Engine CD, Sega CD | | LaserDisc (CHD-LD) | ~50% | daphne (Dragon’s Lair) | | Floppy (CHD-FD) | 60–80% | Rare, mostly converted to IMD/TD0 |
CHD stands for Compressed Hunks of Data . It is a lossless file format designed for MAME/MESS to store dumps of hard disks, CD-ROMs, laser discs, and floppy disks in a compressed, chunk-based manner.
For further reference, see: docs/chd.txt inside MAME source distribution. Official MAME documentation: mamedev.org