SBP 1394 hard drives hang with Windows XP (rare)

Peter Johansson PJohansson at
Fri May 9 07:18:39 PDT 2003

At 01:18 PM 5/5/2003 -0700, Mike Berhan wrote:

>The program worked on both computers; both drives could read up to the 
>full 512K in a single I/O.
>I then modified the app to write back the data from the previously read 
>location.  Both drives hung the same way when the sector count reached 
>257. That matches with your 128K per ORB limitation.

Discussions in Nashua led to the conclusion that the problem is likely 
caused by a bridge chip failure to split > 128 KiB RBC operations into more 
than one ATA command for the attached device. ATA can't transfer more than 
128 KiB in a single command.

>It appears to only be on writes though, at least from what I've seen so far.

It's difficult to understand why a bridge chip should be handling reads 
correctly but tripping up on writes ...

>Perhaps that piece of core logic is used in bridge chips by multiple vendors?

Based on anecdotal experience, I think this is unlikely.

>I would also guess that this problem is not only limited to hard drives, 
>but perhaps to optical drives and other ATA/ATAPI device types as well.

I would agree.


Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

PJohansson at

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