This preserves data and upgrades to latest CHD version (if your chdman is modern).
The output will be raw, uncompressd disk image.
You can also specify full path in command line: chd files for mame
Example output:
If you have an old CHD (v3 or v4) and want v5: This preserves data and upgrades to latest CHD
A (Compressed Hunks of Data) is a lossless compressed disk image format developed by the MAME team. It’s used for storing data from:
Before asking for help, check these four things: chd files for mame
chdman copy -i old.chd -o new.chd