10 Mar
2005
10 Mar
'05
7:30 a.m.
It would be nice to know for historical purposes
exactly which
vendors and when they started putting the firmware on the platter.
I don't think it goes quite that far, most drives only store the
geometry and block maps on tracks that are normally inaccessible to
the user. All the firmware is usually in the memory on the controller.
Seagate and Westarn Digital have had common electronics over different
capacities from about the 1GB drive size. On Seagates the mechanism
was interchangeable between ATA and SCSI controllers, something I used
to exploit to transfer large ammounts of data between my Amiga and PC.
I'll also add my guesses as to why swapping
platters is impossible.
When they build the drive, they clamp the platter on the hub, then
write it with servo information to let it find its tracks. Swapping
platters doesn't work because the two platters will never, ever sit
on the hub exactly the same way.
It doesn't matter, all that's needed is a LL format and all the data
tracks are re-written. Some manufacturers provide tools to do this as
just doing a format from the OS won't do a LL format.
The expensive places must have some way to pull a
platter with the
valuable info to be rescued, then re-align to find the true center,
then attempt to read the data.
No need, they use things like dynamic tracking, even on data only
platters, if needed but disassembling drives is always avoided if
possible.
Lee.
.
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