2.88MB floppies and perpendicular recording - what's the point ?
Re: 2.88MB floppies and perpendicular recording - what's the point ?
The idea was to get greater density of databits on the media - I don't think there was any consideration of compatability - I'm not even sure if the heads in the floppy drive might not have both types of coil set...
Re: 2.88MB floppies and perpendicular recording - what's the point ?
This requires remembering things from a good 25 years ago if not more...
If I remember right, it's not about rotating the head because that's obviously a no go. There would be two possible approaches:
1) Use the two channel erase heads on each side of the actual RW head in order to do some encoding resulting in effective 2 tracks (difference between channel erase left and main, and channel erase right and main), or perhaps better said, a two bit encoding scheme per same space as previously used for one bit. There is probably a difference in geometry of the head as the channel erase heads are intended to localize the magnetisation. This is necessary because the magnetic film of HD and ED floppies is very thin so prone to magnetic domain migration (which results in the actually magnetized portions on the disk moving somewhat from the ideal track shape, reducing the read signal.
So this makes up a sort of encoding scheme that ditributes magnetized areas perpendicular to the track. This is IIRC something that was used for ED drives.
2) The other ide would include using the other side of the disc head to somehow also control the recording and reading flux. I am not sure how that would work without a serious change to the RW head. OR this could use a technique similar to optical drives where a second signal is recorded 'under' the data track to provide track following capability which would be needed to increase the number of tracks per inch. This sort of thing was used in various high density floppy compatibles which never really and truly caught on, such as the Floptical drive, which used an optical system to provide tracking for a modified narrow magnetic head, increasing the data capacity to ~120Mbytes.
If I remember right, it's not about rotating the head because that's obviously a no go. There would be two possible approaches:
1) Use the two channel erase heads on each side of the actual RW head in order to do some encoding resulting in effective 2 tracks (difference between channel erase left and main, and channel erase right and main), or perhaps better said, a two bit encoding scheme per same space as previously used for one bit. There is probably a difference in geometry of the head as the channel erase heads are intended to localize the magnetisation. This is necessary because the magnetic film of HD and ED floppies is very thin so prone to magnetic domain migration (which results in the actually magnetized portions on the disk moving somewhat from the ideal track shape, reducing the read signal.
So this makes up a sort of encoding scheme that ditributes magnetized areas perpendicular to the track. This is IIRC something that was used for ED drives.
2) The other ide would include using the other side of the disc head to somehow also control the recording and reading flux. I am not sure how that would work without a serious change to the RW head. OR this could use a technique similar to optical drives where a second signal is recorded 'under' the data track to provide track following capability which would be needed to increase the number of tracks per inch. This sort of thing was used in various high density floppy compatibles which never really and truly caught on, such as the Floptical drive, which used an optical system to provide tracking for a modified narrow magnetic head, increasing the data capacity to ~120Mbytes.