[cctalk] Re: Nuking an MFM drive with a magnet, format/servo gone?

[Daniel Daigle via cctalk]

Old MFM/RLL drives with stepper positioners generally have no servo. The same 
can't be said of voice-coil positioned drives; they could use any means, 
including hardware optical servos, etc. but often used a surface and a head for 
that purpose... so yes, you can render one of these drives useless with a 
magnet if yours has a servo surface. (This is not the same as embedded servo, 
which places servo information -with- the data on the same surfaces.)