17 Feb
2014
17 Feb
'14
12:54 p.m.
On 02/16/2014 02:50 PM, Tony Duell wrote:
Right... although as Tom suggests, my understanding (possibly erroneous) is
that the address marks are a little more low-level than the sector address
information - and if it was finding data, but confused about what cylinder
it was on, I'd perhaps expect a higher-level "sector not found" or read
error.
Ture, but I am not sure how 'correct' the errors reported by your
controller are. I've had erros that the docuemtnion explains as one thing
and which actually were due to somethign totally differnet.
One thing you might try if you have the appropraite test gear : Monitor
the step and driection lines on the ST412 interface conenctor. Seek to
cylkinder 127, start monitoring and then seek to cylidner 128. If the
signals say it's stepped one cylinder inwards, then the controller is
probably doing the rigth thing. If signals indicate it's doen a lot of
steps outwards, then I would certainy suspect that 128's bit is not
gettign through in the controller.
-tony
Just curious as to what the expert opinion is on this - I've got a
ST412-type drive here (it's a Miniscribe with 615/4/17 ~20MB geometry)
which refuses to read from cylinders 128-255 or cylinders 384-511 - giving
address mark not found errors - although cylinders outside those two ranges
are fine.
The way the faults lie exactly within a couple of specific bit patterns
(01xxxxxxx and 11xxxxxxx) for the cylinder number makes it seem more like a
controller problem to me - but I don't know how much logic there is on a
ST412-type drive, what with the buffered seek ability.
My first guess is that for some reason the controller is losing the 128's
bit from the cylidner register and is, in fact, goign to the wrong cylinder.