8" Floppies

[Eric Smith]

Rick Bensene wrote:
> I've got a batch of 30 brand new 8" Floppies that I can't figure out.
> They are hard-sectored disks.
> The weird part is that the index hole placement is strange on these
> disks.  
>
> They don't work on my Altair 8" drives since the index sensor doesn't
> line up with the hole.
>   
They're double-sided disks.  Not too uncommon.  If you want to see some 
really strange 8" floppy disks, I have a box of Memorex disks that are 
hard-sectored and have the sector/index hole near the outer edge of the 
disk, rather than near the rim.

IBM used an outer-edge index hole on the very first floppy drive, the 
Minnow (23FD), which was a read-only drive used for microcode storage.  
Minnow only stored about 80KB and spun at 90 RPM (vs. 360 for "modern" 
8-inch floppy drives).  The 23FD drive and media were not offered as 
separate products.

Memorex introduced the first commercially-sold 8" read/write floppy 
drive, the 650, and later a 651 with faster seek times.  These were 
hard-sectored and had the sector/index hole near the outer edge, and 
spun at 375 RPM.  I don't know whether the diskettes used by the Memorex 
65x drives were interchangeable with Minnow disks, but my box of Memorex 
disks were presumably for the Memorex 65x drive.  I've heard that the 
65x drive was used in some early word processing systems.

Eric