20 Jun
2007
20 Jun
'07
9:09 p.m.
On 20 Jun 2007 at 22:01, Jim Leonard wrote:
I didn't explain myself well. I used to format
high-quality diskettes
in the early 1990s as 21-sector instead of 18, and I consistently saw
errors after about a year of storage on the inner tracks (and never on
the outer tracks). I wasn't speaking from a storage standpoint, but
rather from a reliability standpoint.
You'd have likely seen nearly the same errors if you'd formatted the
floppies as 18 sectors. The issues of reliability come in when
writing, not reading. 21 sectors gives you something like an 8-byte
gap (i'll calculate it if you want). 8 bytes is .00064 of a track,
so if your spindle speed is too fast, you can easily overwrite the
gap.
But as far as bit-packing density goes, 18 and 21 sectors are the
same.
I would submit that by the early 1990's, there weren't any high-
quality DSHD diskettes. DSED were even worse.
Cheers,
Chuck