CP/M 2.2 Sector Translation Question

Dave Mabry dmabry at mich.com
Thu Jan 22 17:52:38 CST 2009

Off the top of my head (I know, dangerous and unreliable), the sector 
skewing on my Intel MDS was done in the formatting routine.  There was a 
skew offset of something like 3, I think.  The BIOS/BDOS didn't do any 
translation.  It was basically done by writing logical sector numbers 
onto the disks that were not the same as physical sectors.

Remember that the Intel MDS CP/M was the way it was released from DRI.  
Any other OEM could implement theirs differently.


ROBO5.8 said the following on 1/22/2009 6:30 PM:
> Hi,
> I'd like to know if CP/M 2.2 is "Zero" biased when it comes to Sector
> Translation.  Since v2.2 supports Blocking/Deblocking I would assume it has
> to be.  I've looked at lots of code examples via Google and searched the
> documentation but I cannot find a statement to that effect.
> Asking it another way:  The Sector Translation routine is passed the
> requested sector number in Registers B&C.  Does CP/M request Sector 0 or 1
> when it wants the first sector on any track.
> Thanks Robo

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