RE: [t13]: INTRQ

[Eschmann, Michael K]

Title: RE: [t13]: INTRQ

Ditto.  I think too many people are getting their panties in a bunch on this one.

 

-----Original Message-----
From: Curtis Stevens [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 22, 2002 4:58 PM
To: [EMAIL PROTECTED]
Subject: RE: [t13]: INTRQ

I think this whole thing is getting blown way out of proportion.  They guy says he has a host-side chip that where the INTRQ pin does not work.  He appears to be asking if it can still control an ATA device.  He has not said anything about his application or where he plans on using the chip.

The answer to HIS question is simply YES.  The chip can control ATA devices.  Anything else is a matter of efficiency or software compatibility (legacy).

-----------------------
Curtis E. Stevens
Pacific Digital Corp.
2052 Alton Parkway
Irvine, CA 92606

Phone (949) 477-5713
Fax (949) 252-9397

E-Mail: [EMAIL PROTECTED]
WEB: www.PacificDigital.com

The face of a child can say it all, especially the mouth part of the face...

-----Original Message-----
From: Pat LaVarre [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 22, 2002 3:41 PM
To: [EMAIL PROTECTED]
Subject: Re: [t13]: INTRQ

This message is from the T13 list server.

Are many of us talking past each other?

Here lately I can see my luck at writing words that other people read to mean what I meant hasn't been good.

Specifically here below did I somehow say something that could easily be read as contradicting what MKE says here?

The point of designing a device to tolerate a host that does not use INTRQ is (a) to comply with the spec, which as printed by Ansi does not require the use of INTRQ for Pio transfers and (b) to cooperate with Ata/pi hosts available for dramatically less than a Wintel motherboard (like sold for US$ in the single digits).

This is therefore a rational activity, seen to progress simultaneously at various locations worldwide.

Yes a device that floated pin 31 INTRQ of a standard 2x20 connector would be the kind of Evil thing that may be conjectured to explain why commonly Wintel interrupts stay masked.  Me, I never willingly conceived such an abomination, much less mentioned it here.

Pat LaVarre

>>> "Eschmann, Michael K" <[EMAIL PROTECTED]> 01/22/02 04:23PM >>>
This message is from the T13 list server.

You could have no INTRQ pin, but nobody's software would work on it other than your own.  Speaking for "Wintel" systems, the native OS drivers all expect the interrupts to work on a device, so without them the system hangs.  I can't see any OS drivers allowing this, so you will have to have your own driver and the ability to have everyone install the driver before attaching your drive.

As a side note, having a floating interrupt will cause the system to potentially see an interrupt storm. 

So, are you willing to deal with the customer calls on a device like this?

MKE.

-----Original Message-----
From: Pat LaVarre [mailto:[EMAIL PROTECTED]]
Sent: Monday, January 21, 2002 4:34 PM
To: [EMAIL PROTECTED]
Subject: Re: [t13] INTRQ

This message is from the T13 list server.

An Ata/pi device can be designed within the standard to remove the need to use INTRQ, especially for Pio transfers.  The idea is that the host instead

polls port x3F6 AlternateStatus to see when BSY clears.  This works best if
the host in question has a Pio accelerator that makes Pio polling as
efficient for the host cpu as Dma is.

But certainly, to try to operate without INTRQ is to fail ToTalkLikeWindows.
Operating without INTRQ is accordingly a practice which breaks devices in
the real world ... but this practice saves a pin on a chip, which can make
the chip dramatically cheaper by reducing the package size.

By the way, a host chip that does use INTRQ is not Necessarily more
interoperable.  More info is good only if used intelligently.  To the degree
to which BSY and INTRQ are redundant with one another, they can disagree.

Tuning the chip to cope well when they do disagree is a dark art.

Pat LaVarre x4402

>>> liman Munandar <[EMAIL PROTECTED]> 01/21/02 04:53PM >>>
This message is from the T13 list server.

Dear T13:

Does anyone know where I can get more info on the use of the interrupt? The
question I have is whether the INTRQ pin is optional or not. I have a design
using a chip with ATA/ATAPI interface. The INTRQ pin was left open. I wonder
if this is ok. Can an ATA/ATAPI device operate without any interrupt
service?

Thank you in advance.

Regards,

Liman Munandar
Associate Engineer
Dura Micro

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