29 Dec
2010
29 Dec
'10
5:47 p.m.
On 12/29/10 5:26 PM, Chuck Guzis wrote:
Are you perhaps thinking of the Memorex 651 disks with outer-edge
holes and a large "notch" along one side? Those were 64 cylinders,
32-hard-sector, spinning at 375 RPM. Same FM data rate, though (250
Kbit/sec) as the Shugart-style 8" floppies.
I think some of the early IBM models (did they ever get into
production?) used 8 sector holes along the outer edge.
I have several boxes of disks (I seem to recall having discussed them
here before) that I *think* are IBM-labeled but I'm not certain, as I
last actually looked at them many years ago. I know I still have them
and I know where they are, but I'm several states away at the moment and
can't check. Anyway, they have a large notch along one side, and sector
holes around the outer perimeter of the disk.
The only thing I'm not 100% certain of is whether or not they're IBM.
I'll check when I can.
-Dave
--
Dave McGuire
Port Charlotte, FL
ISTR: the 8" drives at least as used in tandy
computers formatted
out to 77 tracks....
Were there 8" drives that had something other than 77 cylinders?
Perhaps the very early IBM ones with the index holes around the
outside edge? Certainly all the ones I've come across were 77
cylinders.