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Curtis, your first sentence is not correct since BSY=1 will not mean "Not
Present", but I believe you do fix that in your second paragraph. The host
"Shall" have a 10k pull-down, so not-present will result in Busy=0.
I agree that BSY=1, no other bits should be checked, but I should have
clarified that in my #2 sentence.
MKE.
-----Original Message-----
From: Curtis Stevens [mailto:[EMAIL PROTECTED]]
Sent: Thursday, May 24, 2001 12:52 PM
To: '[EMAIL PROTECTED]'
Subject: [temp t13] Re: Device Reset
** This is the quasi-official and semi-temporary T13 email list server. **
Mike
BSY=1 means the device is busy or not present. If BSY=1 you should not be
checking the RDY bit because it is technically in an undefined state. In
you example #2, device not present is also an option.
I would also like to point out that if the platform implements the pull-down
on db7, then BSY=1 means that a device is present... The RDY bit is still
unrealiable.
---------------------------------
Phoenix Technologies Ltd.
Curtis E. Stevens
135 Technology Dr.
Irvine, Ca. 92618
Phone: (949) 790-2121
Fax: (949) 790-2006
Internet: [EMAIL PROTECTED]
Web: http://www.phoenix.com
-----Original Message-----
From: Eschmann, Michael K [mailto:[EMAIL PROTECTED]]
Sent: Thursday, May 24, 2001 9:56 AM
To: '[EMAIL PROTECTED]'
Subject: [temp t13] Re: Device Reset
** This is the quasi-official and semi-temporary T13 email list server. **
Shibu, I had a brain-fart. I meant to say "DRQ", not "DRDY" in my message
to you. I don't know why I wrote "DRDY".
1) If BSY=0 and DRDY=0, you may not have a device there.
2) if BSY=1 and DRDY=1, the device is thinking, or if after 30-seconds needs
a reset.
There are most likely other reasons for these conditions, but these are my
favorites.
MKE.
-----Original Message-----
From: SHIBU BABY [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, May 23, 2001 10:02 PM
To: '[EMAIL PROTECTED]'
Subject: [temp t13] Re: Device Reset
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Eschmann, Michael K [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, May 23, 2001 8:57 PM Wrote
>>>>DRDY does not have to be 1, in fact it should be 0 in order to >>>>send
a command. BSY=0 and DRDY=1 indicates ready to transfer >>>>data,
I think the DRQ bit indicates ready to transfer data.
>>Hale Wrote
>>>The Exec Dev Diag command says that a device should execute its
>>>"diagnostics". In the process of doing that it may need to become "not
ready" and it may need some time to become "ready" following the end of the
command. The same is true for the Hardware and Software resets.
This kind of information is not documented in ATA spec. I can't understand
why this delay to set DRDY.And I don't think it is good answer that "it may
Ready and it may not be Ready". I think Hale is saying this by the
implementation of hard disks by different manufactures. If yes, this is a
violation of ATA spec.The better way is to document all this in ATA spec.
Other wise a new comer would depends on this kind of mail discussions.
>>Hale Wrote
>>DRDY=1 is not a prerequiste for any command on an ATAPI device. Any reset
and several commands cause an ATAPI device to set DRDRY=0 and the device is
not allowed to set DRDY=1 until after certain other commands, like the
PACKET command.
Why it is not allowed to set DRDY.Just not setting is not enough.
Can u explain what is the reason for not setting. This is also not
documented in ATA spec. I think it may be documented in other specs.As per
ATA spec I can understand that DRDY=1 for ATA/ATAPI device. Because every
command descriptions, there is prerequiste for BSY=0 DRDY=0. The best
example is IDENTIFY PACKET DEVICE. This means one should refer other
available spec before doing any operation command to ATA/ATAPI. If yes then
why ATA/ATAPI spec?. No details of ATAPI. Just saying ATA/ATAPI.and only a
PACKET command .
Thanks
Shibu
-----Original Message-----
From: Hale Landis [mailto:[EMAIL PROTECTED]]
Sent: Thursday, May 24, 2001 3:01 AM
To: [EMAIL PROTECTED]
Subject: [temp t13] Re: Device Reset
** This is the quasi-official and semi-temporary T13 email list server. **
On Wed, 23 May 2001 15:18:44 -0600, Jim Castleberry wrote:
>Related question: what's the purpose of the SET FEATURES command that
>tells the drive what mode the host is going to use? Does it change
>drive behavior at all? I can imagine ways the drive could use the
>information to increase performance, but do they really?
Yes, there have been drives that required the Set Features command
otherwise they would not operate properly at PIO mode 3 or 4 speeds
(they would corrupt data). This is why to this day a host should
always issue the Set Features command if it really wants to use PIO
mode 3 or 4.
>The host isn't required to issue that SET FEATURES, is it?
Not required but it is the safe thing to do. And it is only a few
bytes of code and takes all of a few microseconds.
>Someone correct me if I'm wrong... Didn't Windows 9X ship with DMA turned
>off by default? And even W2K appears to leave it off by default for most
>ATAPI devices. Linux left it off by default until recently. That's most
>of PC Storage right there that's not using DMA.
Most ATAPI devices seem to be operated at PIO mode 0 even on new fast
systems. And because most ATAPI devices are very slow (even a 50x CD
is extremely slow) and because ATAPI devices generally do not work on
the same cable with another device this really should not be a big
problem, certainly not a bit impact to hard disk performance on the
same system.
*** Hale Landis *** [EMAIL PROTECTED] ***
*** Niwot, CO USA *** www.ata-atapi.com ***
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