Floppy disks again

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Tue Oct 12 09:49:15 1999

> Ok, so 48 TPI media has low coercivity, so a 96TPI head with higher
> write current will cause the adjacent tracks to erase because of
> the magnet fringes from the head. These magnetic fringes aren't
> strong enough to effect 96TPI media because it has a higher
> coercivity.

???? reread that and see if it makes sense to you...

There are two media for 96tpi, one for DD and lower and is the SAME
magnetic material as 48tpi. THere is also the 1.2mb media and this is
VERY DIFFERENT and incompatable with any other drive or density.

So if we ignore 1.2mb media and the oddbal spindle speeds and data rates
that go with it we come down to one media (softs sector) and 6 different
drives over the years. They are:

        48tpi single sided (sa400)
        48tpi double sided (sa450)
        96tpi single sided (teac Fd55E or DEC RX50)
        96tpi double sided (teac FD55F)
        100tpi single and double sided models (micropolus I think)
 
  *there may have been others mostly forgetable. Apple and other GCR
   unique drive not included as they are NOT standard floppies as often
   they were standard drives with differences introduced.

They all record data at roughly the same linear density (FM at 125kbs or
MFM at 250kbs all rotate at 300rpm) and differ largely on the number of
sides, width of track and absolute position for tracks greater than 000.

Allison
Received on Tue Oct 12 1999 - 09:49:15 BST