Date   : Mon, 29 Nov 2010 11:48:41 +0000
From   : jim@... (Jim Hearne)
Subject: Harddisc fakery using a microcontroller

  I repaired a lot of PC's in the ST506 era and i can't ever remember a 
disc interface built into a motherboard, it was always on a ISA card.
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.
This was a major pain if the control card failed and you didn't have one 
the same.
I guess it was because the lower level format code was in the Bios for 
the control card and there wasn't a well defined spec for it at the time.

Jim



On 26/11/2010 19:18, Rick Murray wrote:
> On 24/11/2010 10:38, Phil Blundell wrote:
>
>
> I wonder, in the case of ST506 units, if it wouldn't prove simpler to
> work up the chain to whatever the disc controller is, and replace that
> with something newer? In essence, that is what I was thinking regarding
> the PIC/AVR and SCSI, the difference here being where exactly the disc
> controller is located (SCSI drives having some smarts on-board). I guess
> you're a bit stuffed in this respect if it is welded directly to the
> mainboard and not as a plug-in...
>
>
> Best wishes,
>
> Rick.
>