4 Feb
1998
4 Feb
'98
12:51 a.m.
At 07:57 AM 2/4/98, you wrote:
Do you mean that XT drive will run SD whn run off of
a SD controller and
the disks will be compatable? They would be great. I knew a XT drive
would read and write but I thought the disks would be incompatible with a
disk from a SA 400.
Yup.
It's the 1.2m 5.25" drives that are weird.
Yup.
Yes, 17 sectors and odd number of tracks. The track
spacing is 1/2 of
that of the 180 and 360K drives and the first track is in a different
location.
Nope. 1.2Meg 5.25" HD drives are 15 sectors per track, and the standard 80
tracks (at the standard 96 tracks per inch), just like 720K DSDD 80 track
5.25" drives.
I heard rumors that the reason they went with 15 spt is because they tried
doubling the density to 18 spt (like the 3.5" floppies) but the formats
were (at best) highly unstable and of poor quality. So they just dropped
the SPT to something that was more reliable... but that's just a rumor I
heard.
The # of 17 spt IIRC is from MFM hard drives, and RLL hard drives used 26
spt. I also remember that (at least some) 8" floppies used 77 tracks, but
5.25" floppies have used either 35, 40, or 80 tracks as a standard.
Hope this helps,
Roger "Merch" Merchberger
--
Roger Merchberger | Why does Hershey's put nutritional
Programmer, NorthernWay | information on their candy bar wrappers
zmerch(a)northernway.net | when there's no nutritional value within?