RS>> Sectors are normally numbered form a
RS>> base of 1 for various historical reasons.

PE>>> Do you think that sectors are:

PE>>> A) 64 sectors, numbered 0 to 63

PE>>> B) 64 sectors, numbered 1 to 64

PE>>> C) 63 sectors, numbered 0 to 62

PE>>> D) 63 sectors, numbered 1 to 63

PE>>> Last thing I remembered you said A.

RS>> Nope, B.

PE>> Ok, close enough.  What evidence do you have of this?

RS> The most obvious is sector editors where you specify the
RS> sector in terms of head, cylinder and sector. The only one
RS> that starts from 1 is the sector. LIke Nortons DiskEdit.

No, I meant that it is 64, not 63.  I say it is 63.

PE>> I have been using D in PDOS, and it appears to be working.

RS> Depends on how you decide it 'appears to be working',
RS> if you dont rigorously test for the missing last sector....

I am doing address translation from absolute number (as used in the fat) to
physical number (as used by the BIOS), in order to boot PDOS. It is all
working.

RS> Its also complicated by what level you are doing the direct access at.
RS> There is lots of translation and faking with a modern IDE drive. You
RS> dont actually have a fixed number of sectors per track anymore, that
RS> varys in bands across the platter and that is faked up into something
RS> completely different at the level of the commands down the cable to the
RS> drive. Even more dramatically if the drive is being used in LBA mode.

Yeah, I'm not talking about that, I'm talking about what the
"user" sees as the number of sectors/track.  It is shown as 63,
and I just want to know if that means 63 or 64.  BTW, the floppy shows as
18.  Do you think that means 19?

BFN.  Paul.
@EOT:

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