15 Dec
2005
15 Dec
'05
9:32 a.m.
On 12/15/2005 at 7:42 AM Allison wrote:
Any PC controller that can do 720k 3.5" format can
do
8" as it's the same data rate. it's not what chips was
used it's how it was used.
Whoa. Sorry, I couldn't let this one go by unanswered.
8" drives use a 500K data clock rate, not 250K like the DS2D 720K 3.5". A
controller that supports 1.44M DSHD 3.5" should do just fine on 8". While
there were early 8" drives that used a lower clock rate, they were pretty
much gone by the time of the dawn of the PC. FM support with a modern
controller is a somewhat different kettle of fish. The nearest AT medium
to the 8" drive would be the 5.25" high-density diskette, which also spins
at the same rate--360 RPM.
That was the beauty of the NEC APC line--from 8" right down to 3.5", the
data format didn't vary one iota. The NEC 9801 floppies still record 1.3MB
on a 3.5" drive spinning at 360 RPM.
But the PC-XT 8" drive controllers were a special beast, honest.
Cheers,
Chuck