I've been messing with a VersaFloppy II board and trying to get it to work with my 5 1/4" drives. I've been having some issues, however. I think it might be best if I first explain some assumptions I have about drives and media, and if I say something wrong please correct me:
- There are a few commonly available 5 1/4" drives. I have three: a TEAC FD-55FR-511-U 720KB 300RPM drive, a Toshiba ND-0801GR 1.2MB 360RPM drive, and a Fujitsu M2553K 03B 1.22 MB drive that may not be working.
- The VersaFloppy II is designed to work with 8" or 5 1/4" drives. With the right software, it should be able to control 360 KB, 720 KB and 1.2 MB drives.
- John Monahan's VersaFloppy II diagnostic program is a recommended way to test out and control your drives. I've gotten this running, but I'm not sure it works with 720 KB or 1.2 MB drives.
- Drives rotate the disks at either 360 RPM or 300 RPM. 300 RPM results in a lower density. Some drives have a jumper to switch speeds (my Toshiba) and some have a pin that they listen to to vary the speed. The VersaFloppy II's IOByte has a bit that identifies whether it's high density or low density, which is then sent to the floppy disk. Any low density format should be on a drive that rotates at 300 RPM.
In addition to the drives, here are my assumptions about disk media:
- There are a number of hard-to-identify disk formats: Single or "High" density, Double or "Quad" Density, and each of these can be Double or Single Sided.
- Any disk media starts out as a blank slate of magnetic material, with either DD or SD media, which are physically different. When you format a disk you create the tracks and sectors--they're not created that way at the factory.
- A DSDD disk can work as 720 KB, 1.2 MB, or 360 KB.
- A STEP command sent to a 360 KB drive will rotate the stepper motor twice as much as on a 720 KB or 1.2 MB drive. This is because the RW head is fatter, and needs to go twice the distance to avoid magnetic interference. So the VersaFloppy II controller needs to double-step a 700 KB or 1.22 MB drive if it thinks it's talking to a 360 KB drive.
- Double stepping a drive occurs by the user's software passing the correct parameters to the VersaFloppy II and its WD 179x controller chip.
Before I get deeper into this, please let me know if I have some fundamental misunderstandings.