Image NEC OS9
Is it rubbish though? This is the first sector of the disc, and it does look to contain an OS9 type boot block. The first three bytes are the number of sectors on the disc, encoded high byte first, &13380 being the total number from this disc's geometry of 615 cylinders and 4 heads, at 32 sectors per track which is the figure supported by the Xebec controller.