On 9/1/22 18:43, Mike Katz wrote: > Taking my memory back to the early 1980's and the Western Digital floppy > disk controller chip family (177X single density and 179X double > density). I wrote the 6809 drivers for Gimix Flex. The controller chip > used the index pulse for sector zero position and for timing out a > failed read or write command. I don't recall if that controller chip > family could handle hard sectoring (one hole per sector) or not.
All WD and NEC floppy controllers use the index hole for formatting as Fred mentioned. Further, I believe that three passes of the index hole while attempting to read or write gets you "Sector not found" if the address ID isn't detected. See datasheet and app notes for details. No WD or NEC floppy controller handles hard-sectored recording schemes. HOWEVER: A few years back, I was sent a bunch of 8" HS disks that were really puzzling--the sector ID address headers didn't line up with the sector hole timing. In fact, they were WAY off. It turns out that some 8" drives can be set to separate the sector holes from the index hole (separate output pins for index and sector). Doing so, gives you what amounts to a soft-sectored floppy, regardless of what the physical object is. I know that I used a Siemens FDD-200 drive jumpered accordingly to read them. Good times. --Chuck
