The .IMG disk image files are in logical sector format.

The .DSK disk image files are in physical sector format with a sector
interleave of 2, and a 6 sector skew between tracks. Logical sectors
start at track 1, sector 1, go to up to track 76, and then back down
to track 0.

For use with SIMH the physical sector format .DSK image files should
be used when mounting the image on an RX01 or RX02 device.
