RL02-USB Controller Status/Problem

Johnny Billquist bqt at update.uu.se
Tue Apr 7 13:38:33 CDT 2015

On 2015-04-07 19:21, Pete Turnbull wrote:
> On 07/04/2015 16:59, Johnny Billquist wrote:
>> You are thinking of/referring to how the file system works. The bad
>> block list on the last track is not directly used by the system, since
>> this is different from one device to the next.
>> RL drives have bad block information on the last track. It is not OS
>> dependent.
> No, but how it's used is possibly OS dependent, as I wrote.  As far as I
> can tell, only the /manufacturing/ bad block data is stored in the last
> track.  RT-11 copies that to the home block, merged with any other bad
> block information found later, and uses what's in the home block.  That
> means whatever reads or writes the disk has to fetch the bad block data
> from the home block (the DL.SYS driver stores that in memory while it's
> resident, and updates it when it knows a pack is changed).  Of course
> here we're only talking about RL01/02 and other drives that have such a
> table.
> Maybe it's different for RSX; I don't know enough about the innards of
> RSX to say, hence my question, "RSX-11 may not be the same?"  But I
> think Paul has provided me the answer.

How it is used is definitely OS dependent, but the information is as I 

See "RL01 RL02 Disk Subsystem Users Guide".
Section 1.5 Bad Sector File, page 1-6 to 1-8.

5 copies of the factory written bad sector info, and 5 copies of the 
field written bad sector info.

Now, RT-11 might not be using the information right, I wouldn't know. I 
think that any Unix system definitely did not use the information right.


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