A D71 file is a disk image format specifically designed for use with Commodore 128 emulators and vintage computing preservation tools. It represents a complete, raw sector-by-sector copy of a 5.25-inch floppy disk used by the Commodore 1571 disk drive. Unlike the more common D64 format used for the Commodore 64's 1541 drive, the D71 format supports double-sided disks, providing a storage capacity of approximately 340 KB, which is double the 170 KB capacity of a standard D64 image. This format is essential for preserving legacy software, productivity tools, and operating systems originally written for the Commodore 128. It captures the exact physical layout of the disk, including the directory structure, BAM (Block Availability Map), and individual files, allowing modern computers to interact with vintage software through emulation. Users typically utilize these files to load software into emulated environments like VICE or to transfer data back to physical Commodore hardware using specialized hardware interfaces such as the ZoomFloppy.