4 Feb
2015
4 Feb
'15
12:52 p.m.
One effort to help a little is "write
precompensation". On inner
tracks, if adjacent flux transitions that would end up real close
together are written slightly out of position, slightly further
apart, it can help reduce the problem of flux transitions being
too close together. As part of doing that, there is a signal
available called "TG43" ("track number greater than 43") to help
decide when to enable precomp.
In every 'normal' floppy disk system (read : ones using shugart SA400 or
SA800 type interfaces), write precompensation is done by the controller
electronics, not the drive. So while an LSI controller chip may well have an
output to enable the precompensation electronics on the controller board
that would not be a reason to pass it to the drive.
On standard 8" drives, the TG43 signal on the interface connector does,
as Chuck said, reduce the write head current.
-tony