This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
You can use a whole-disk copier such as Disk Muncher to copy from one to the other. For .nib --> .dsk, the .nib must not be a copy protected image. For a .dsk --> .nib copy on an emulator using most whole-disk copiers, one result will be to set the Volume Number of the .nib to the default assigned to the .dsk. For example, converting a normal .dsk image this way will result in a .nib with VN set to 254. If you want to 'convert' from .dsk to .nib without changing the VN of the .nib, use a copier that transfers just the contents. The old Apple program, COPYA, will do this if the program is modified to eliminate formatting of the target disk. Change the Line which does the INIT (usually Line 250) to ... 250 FT= 1 ----------------------------
 
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