SORT by INDEX HOLE POSITION! On Wed, 17 Sep 2003, Nico de Jong wrote: ALMOST. There is no visible difference between SD single density v DD Double density. But, if you take a look at SS Single sided v DS double sided, the index hole is in a different place! Most double sided drives have BOTH sets of index holes, and therefore can format a DS disk as single sided, if so requested. BUT, some single sided drives can NOT format a disk that only has the DS index holes. That is further complicated by the fact that after a disk has been formatted (or reformatted after you bulk-erase them) that the index hole can then be ignored, permitting using disks with index holes that don't match the drive! (after they were formatted on a different drive) Therefore, sort them by the index hole position, and you will have successfully identified which ones can be formatted as SS v DS in the appropriate drives. -- Fred Cisin cisin(a)xenosoft.com XenoSoft http://www.xenosoft.com PO Box 1236 (510) 558-9366 Berkeley, CA 94701-1236

On Wed, 17 Sep 2003, Bryan Pope wrote: Examine an 8" diskette. Draw an imaginary line on it, to check for symmetry - if you were to put the disk in upside down, would the holes line up? You will find that the write-access slot is symmetrical, but the write protect notch is NOT symmetrically placed, nor is the position of the index hole. IIRC, (unless I just got it backwards!) the index hole of the SINGLE sided disk is CLOSE to the center line, but the index hole of the DOUBLE sided disk is visibly substantially further away from the center line. It is possible to punch additional holes to convert a SS diskette into a DS, or to convert a SS into a "flippy". The 8" version of the "Berkeley Microcomputer Flip-Jig" is substantially rarer than the 5.25' version. Useless trivia: in an episode of the "Computer Bowl" quiz show, NOBODY on Bill Gates' team had any idea where the write protect notch is on an 8" diskette! Hint: where would be the worst place for it to be to cause problems when the write-enable tab falls off in the drive? NB: 8" has a write protect notch that can be covered with a write-enable tab, v 5.25" has a write enable notch that can be covered with a write protect tab. Some drives (SA455) have jumpers to permit reversing that!

On Wed, 17 Sep 2003, Bryan Pope wrote: Even then, the terminology can be ambiguous. "Jacket" is sometimes used to refer to the "sleeve", or "pocket" that the disk is stored in. I was, indeed, referring to the felt? lined cardboard? in which the mylar? spins. I remember, years ago, a student in the college lab removed the round mylar to put it in the drive. When questioned, she showed instructions from her instructor to "remove the disk from its cover". When further questioned about why she didn't realize the error based on the difficulty, she pointed out that modern potato chip bags can be equally stubborn. A few years ago, the lab staff insisted on removing ALL 5.25" drives from the lab, because students (and even one instructor!) were trying to put CD-ROMs into them!

On Wed, 17 Sep 2003, Nico de Jong wrote: Quite the contrary! A quick glance at an 8" disk will tell you its density by the position of the index aperature in the disk jacket. A Single Sided disk has the aperature 7 degrees clockwise of the 12 o'clock position, while a Double Sided disk has it located 26 degrees clockwise of the 12 o'clock position. In other words, SS is at about 1202 and DS is about 1307 hours. - don

On Wed, 17 Sep 2003, Fred Cisin wrote: Quite so! Brain fart. And I have never experienced any problem considering them to be interchangeable in 8" usage. - don