Where's my confusion may lie is how each drive uses:
- Write-enabled notch (Requires 1 or 2 notches? When? Why?)
- Index Hole (Requires 1 or 2 index holes? When? Why?)
Here, the single sided drive as mentioned above would be the 1541 drive. However, the 1571 has 2 heads unlike the 1541.
Question #1: Does this mean for a 1571 drive, the disk need not be flipped since the 1571 has two heads (where internally it is flipping the disk simply by using the second head)? But the concept of a Flippy Disk leaves me with another question: since the 1571 has dual heads and can write to both sides of a double sided disk without being flipped, how does one distinguish a "Flippy Disk" from a disk that was written with two heads like a 1571? Or, is there somehow no difference?
Question #2: With regard to the write enabled notch and the 1571 drive, do you need one notch to write to side A, and a second notch to write to side B? Or, would you only need one notch for a 1571 drive to be able to write to both side A and side B considering you don't have to flip the disk over?
I'm of the understanding, that for the 1541 drive you need TWO write enabled notches to write to both Side A and Side B. However, to write to side B, you must flip the disk for the 1541 since it only has one head.
But what about the index hole for Side B to be read by a 1541 vs a 1571 ...
The Index Hole:
According to Wikipedia, "For disk operating systems that do use index sync, a second index hole window has to be punched in both sides of the jacket, and for hard-sectored formats, an additional window must be punched for the sector holes". Can someone help to clarify this?
Question #3: Assuming you did flip the disk for the 1541 to read Side B, wouldn't the drive FAIL to write to the disk since there is NO secondary index hole? Otherwise, does this mean for the 1541 when reading Side A it is index synched to the index hole of the disk where for Side B it is NOT index synched? When would a second index hole have to be punched? I have seen plenty of Commode disk with simply two notches on both sides and usually only ONE index hole. If the 1541 simply ignores the index hole for Side B, then why would a 1541 drive even care about the index hole at all even for Side A? What is meant by "hard-sectored" formats?
Question #4: Does the 1571 have two index hole sensors just as it has two heads? At this point, for all I know the 1571 is index syncing on the first index hole in order to write to Side B since it can still SEE the first index hole considering it has dual heads and does not need a disk to be flipped to read/write to Side B. But then, how does the 1541 handle this with regard to the index hole it can't see when the disk is flipped? Hmmmm
Question #5: It would seem that some floppies written by professional copiers/duplicators, do NOT even have notches at all, but may have DUAL index holes and still contain data on both Side A and Side B. If a disk has two index holes, does that mean it's a Flippy Disk? Or, if it has data on Side B with one index hole what does that even mean then? A picture of a professionally written disk with NO notches yet with 2 index holes found here: https://en.wikipedia.org/wiki/Floppy_di ... y_Disk.jpg
Finally, I guess my underlying confusion is on how to determine when looking at a physical floppy disk whether it is a Flippy Disk or not and what a "Flippy Disk" even really means with regard to the required notches (1 or 2?) and index holes (1 or 2?) from the perspective of use in the 1571 and 1541 drives. If the 1571 can indeed write to both sides of a disk without flipping it, would such a disk still be considered a Flippy disk? Or the ability of the 1571 to write to Side B written in a different format? In other words, is Side B always written in the same format by a 1571 and 1541 drive or are there different formats (possibly due to how a single head drive writes to side B vs how a dual headed drive can write to side B?)
Where am I going with this? Eventually, I want to preserve these Commodore disks utilizing Kryoflux but am currently VERY confused about this whole Flippy disk concept. In reading through the forums, it seems that since the 1571 has dual heads, I would NOT need a flippy modded PC disk drive to use Kryoflux to image both side A and B of the disk as long as the disk was written by a 1571. I believe I have read that both Side A and Side B can be read in a single pass a drive that is NOT flippy modded. However, if the disk was written by say a 1541, I would need a Flippy modded PC disk in order for Kryoflux to be able to image Side B (the Flippy Side).
A lot of the disks I have were written by a 1571 drive. I've yet to understand how to determine when looking at some of these disks if some are Flippy Disk and some are simply not flippy disks but may still have data on Side B since the 1571 can magically write to Side B. How this is all done is what I'm better trying to first understand.
Someone please help set me straight if possible!