disk editor
computer program that allows its user to read, edit, and write raw data (at character or hexadecimal, byte-levels) on disk drives (e.g., hard disks, USB flash disks or removable media such as a floppy disks)
en-GB/ˈdɪsk ˈɛdɪtə/
en-US/ˈdɪsk ˈɛdɪtɚ/