Geert Uytterhoeven wrote:

quoted

Apparently some IDE drives (e.g. a pile of 80 GB ST380020ACE drives I have
access to) advertise to support LBA48, but don't.
One problem with those drives is that the lba_capacity_2 field in their drive
identification is set to 0.

Andre Hedrick replies:

Actually this issue an errata correction in ATA-6 and changed in ATA-7.

48-bit command set support is different than capacity.

Hmm. I read in my copy of ATA7:

 6.16.55 Words (103:100): Maximum user LBA for 48-bit Address feature set
 Words (103:100) contain a value that is one greater than the maximum LBA
 in user accessable space when the 48-bit Addressing feature set is supported.
 The maximum value that shall be placed in this field is 0000FFFFFFFFFFFFh.
 Support of these words is mandatory if the 48-bit Address feature set is supported.

Do you read differently?