Date   : Mon, 29 Nov 2010 15:34:29 +0100
From   : rick@... (Rick Murray)
Subject: Harddisc fakery using a microcontroller

On 29/11/2010 12:48, Jim Hearne wrote:

> The other problem is though that almost every MFM and RLL control card
> disc format was incompatible with any other.
> You had to have the same make and model of control card that the drive
> was low level formated with, otherwise you couldn't read the drive.

Not *so* different these days, if you consider the "controller card" 
sits directly under the drive in modern hardware. One moment of lack of 
concentration and a manufacturer who annoyingly puts the power socket a 
different way around to all your other kit, you could find you've 
delivered 12V into the logic before realising the plug won't fit.

I only did this once, after switching IDEs for a disc that kept failing 
its format (so some consolation it was probably buggered anyway), but 
I've seen others toast drives this way a number of times.

...and if you can't find an *exact* same model of drive, you're stuck. 
The controller boards aren't interchangeable. Even then, I wonder if 
there isn't something held on flash to map peculiarities of the specific 
unit - never tried replacing a drive board, I don't have two identicals 
to try.



Best wishes,

Rick.

-- 
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...