Date   : Tue, 23 Jun 2009 10:22:36 -0500
From   : jules.richardson99@... (Jules Richardson)
Subject: reading data from old hard disk

Phil Blundell wrote:
> Now, though, I discover an additional problem: the disk is using
> 256-byte sectors whereas obviously the PC is set up to expect 512.  I
> can modify the driver source easily enough but I'm not sure whether the
> controller card itself can be made to work with 256 bytes per sector.

MFM disks tend to be somewhat tied to the controller which (low level) 
formatted them, sadly - so yes, it's entirely possible that the controller's 
making some assumptions about the low-level data format on the drive and barfing.

Couple of options:

1) Adaptec bridge, BBC micro, the modified xfer software[1] (which works with 
hard disks), and serial-link the data across to a modern machine,

2) Adaptec / Xebec / OMTI bridge [2], SCSI controller, PC running whatever 
2.4.x kernel it was that was reported to work (by Rhys, IIRC) with the 
Domesday player a few weeks ago, then whip up some C code to read raw blocks 
from the drive using the sg interface.

[1] it's supposed to be for ADFS, but I think it's all sufficiently low-level 
that you can just hack in the start and end block and let it run - assuming 
that the Adaptec bridge will talk to the low level format on the drive. I 
remember using it that way to drag data across from an Econet server drive.

[2] Some of them allowed the sector size to be specifed via jumpers, others 
via software. They were generally "mostly SCSI", but the read/write commands 
are generally standardised - if it works with the Domesday setup, it should 
work with one of the SCSI bridges. Again, needs the low-level format of the 
drive to be something that the bridge can make sense of, though.

What's the history of this drive - is that HDFS as in SJ Research, or HDFS as 
in hierarchical filesystem?

cheers

Jules