Doug Spence wrote:
 Hi,
 How common are 16-sector hard sectored disks?
 I found some disks for my AES 7100, and that's what they are (17
 holes!). 
You didn't say whether they were 5 1/4" or 8" floppies (I'm not familiar
with the AES 7100.) The 5 1/4" disks were used on, among others, the Vector
Graphic S-100 computers.