"Imaging" a MFM drive?

[Philip Pemberton]

Joachim Thiemann wrote:
>    I have an old MFM drive (MiniScribe 8425) hooked up to a Xebec
> 1210C 8-bit ISA controller, pulled out of my Amiga 1060 sidecar,

[...]

 > I can get a hold of a 1998-era PC, mainly PCI but
> still with a single 16-bit ISA slot - but I have no idea if there is
> any software that can then get the bits off the drive.

There are a few things I'd be worried about here...
   - You need to know what parameters were used when formatting the 
drive. Usually these will be the ones printed on the drive label (or in 
the instruction book) but sometimes e.g. the cylinder count is reduced 
to get around bad cylinders, and so on.
   - As it's an 8-bit card, it should work fine in a 16-bit ISA slot. 
Problem is, it may well conflict with the motherboard's onboard IDE 
controller (if it has one, which is likely). At the very least you'll 
need to configure the Xebec card as a secondary controller, then turn 
off the secondary IDE controller in the BIOS.

 > ISTR that the
> xd driver in linux was broken or removed, or is the card WD100x
> compatible?

It's still in the 2.6 kernel source... No idea if it works, but in any 
case you'll probably have to build a custom kernel to use it (I'll bet 
most Linux distros won't compile it in by default).

 > Will the 8-bit BIOS on the card
> work in a Celeron class machine?

Should do. Worst case, pull the EPROM chip or flip the ROM_DISABLE jumper.

 > If somehow I find a sufficiently old
> PC, how can I get the data off the non-MS-DOS partition?

$ su -
# dd if=/dev/hd(whatever the Xebec comes up as) of=/root/hdd_image

Then copy hdd_image off onto another (faster) machine for processing.

That'll give you a raw dump of the contents of the drive. Then you just 
have to figure out the partitioning and data structure (even/odd word 
storage, and so on)...

It should be possible to search the drive image block-by-block to find 
the Amiga FS superblock -- you can certainly do it for FAT{12,16,32} and 
the Linux Extfs variants because there's static data in the superblock.

-- 
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/