18 Mar
2009
18 Mar
'09
5:14 p.m.
Fred Cisin wrote:
IFF you want to recover the old data, and/or use the
old hard drive
without a low-level reformat, then you will need to specify which hard
disk controller with more than "8 bit". Unlike AT (16 bit), the XT hard
disk conrollers were not interchangeable. Not even between related models
of Xebec.
That's mostly true, in my experience, though also not to do with the
width of the data bus :) but more to do with the type of disks, what you
say would mostly be true for MFM or RLL disks, of which most 8 bit
controlers are, but would also apply to 16bit MFM/RLL too.
But it would not apply to for example SCSI, or IDE, though for 8 bit IDE
you do need a compatible drive.
In my experience I have also found that the rule isn't hard and fast for
MFM drives, for example I can read the disks from my Altos unix box on a
PC with a compatible WD MFM chipset, though the slight complication is
that the Altos disks are 16 sectors/track rather than the more common 17
on a PC.
Mind I really only have experience of WD chipsets, as they where most
common here in the UK, cirtainly I have other MFM/RLL cards, but only
thew odd one or two, whereas I have several WD based ones.
Do I remember the original Xebec ones having a Z80 on board, so maybe
they where partly software driven, and the incompatibility was due to
different versions of the software.
To the OP: you said that you have tried different drives, have you also
tried different cables, I'm asuming so but you didn't say so may not of
thought of it :)
Cheers.
Phill.
--
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
"You can twist perceptions, but reality won't budge" -- Rush.