What is "bit nibbler"

n. (context computing English) A computer program that defeats some copy protection schemes by reading a disk one bit at a time, and directly interacting with the disk drive hardware.

A bit nibbler, or nibbler, is a computer software program designed to copy data from a floppy disk one bit at a time. It functions at a very low level directly interacting with the disk drive hardware to override a copy protection scheme that the floppy disk's data may be stored in. In most cases the nibbler software still analyses the data on a byte level, only looking to the bit level when dealing with synchronization marks (syncs), zero-gaps and other sector & track headers. When possible, nibblers will work with the low-level data encoding format used by the disk system, being Group Code Recording (GCR - Apple, Commodore), Frequency Modulation (FM - Atari), or Modified Frequency Modulation (MFM - Amiga, Atari, IBM PC).