> > (irq_stat 0x40000001)
>
> IRQ status of the chip
> > tag 0
> Tag (or zero for non NCQ commands)
> > cmd 0xb0
> The ATA command number issued
> > emask 0x1
> Internal libata error category (used to decide what to do to
> recover)
> > stat 0x51
> Status register of drive
> > err 0x4
> Error register of drive
>
>
> You want the ATA specification document from T13 (
www.t13.org)