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DRQ with ERR means ERR?

BSY=0 ERR=1 always means "the command ended with an error" - doesn't matter what DRQ or any other status bit says - except DF (Device Fault) overrides all status bits when BSY=0.

In what sense has this command "ended"?

Until DRQ is clear, the host can't proceed with another command, by the rule that forbids writing x1F7 Command while BSY|DRQ is set?

And what of the ATAPI devices whose firmware doesn't get a chance to clear ERR until after the DRQ of Command Out?

And if DRQ with ERR means ERR, why then SRST?  SRST in reaction to an
unexpected DRQ I understand - but in reaction to an unexpected ERR?

ATA tradition - whenever something strange happens try a Soft Reset before retrying the command.

News to me, thank you.

Pat LaVarre



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