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    Just FYI, the 1571 does not use Commodore's own disk GCR format in CP/M mode. Rather than that, it has an extra WD1770 disk controller chip that handles standard MFM disks. So it can read disks created by a standard 360KB dual-head double density PC disk drive. So you don't need to create a D71 image. Commented Nov 10, 2024 at 2:03
  • Ah, that makes sense. Perhaps you could post an answer showing how to use cpmtools or similar to create and put things on to such a disk image? Commented Nov 10, 2024 at 8:45
  • What ctools does is crumpling the sector lineup of D71 images that way so it maps to plain MFM disks. You can see that from that a complicated mapping is done for MFM (C128) disks and no mapping is done for GCR (C64) disks. — Skip that D71 step completely and produce plain MFM disks with bog standard 40 tracks and nine 512 byte sectors per track with a PC 5¼" disk drive. Commented Nov 10, 2024 at 22:56