for anyone wanting to try David's MFM emulator in an HP MFM 7945 disk box, here is the format, determined from reading a Vertex V170 drive from one --sectors 32,0 --heads 7 --cylinders 987 --header_crc 0xffff,0x1021,16,0 --data_crc 0xffffffff,0x140a0445,32,5 --format WD_1006 --sector_length 256 The 7945 is notoriously flaky because of the Vertex drives.