Larry
If BSY=0, you can issue EXECUTE DIAGNOSTICS. This should cause a transition to BSY=1 within 400ns. This informs the host that something is attached to the cable. This means that you do not have to wait forever waiting for RDY=1 or timeout on some other condition.
-----Original Message-----
From: Larry Barras [mailto:[EMAIL PROTECTED]]
Sent: Thursday, July 12, 2001 6:17 PM
To: [EMAIL PROTECTED]
Subject: [temp t13] Re: Are devices allowed to go busy on their own?
** This is the quasi-official and semi-temporary T13 email list server. **
Curtis,
I tend to favor the drive behavior of BSY=1 while DRDY=0, in other
words, not clearing BSY until the device is ready.
Execute device diagnostics doesn't seem to serve any useful purpose
that I can see. It doesn't help with enumerating what's on the bus
anyway.
>Jim
>
> There are 2 behaviors that are common during spin-up. The one I
>support strongly is the BSY=0, DRDY=0. This lets you issue EXECUTE
>DIAGNOSTICS immediatly. Unfortunatly, some drives appear to hang...
>The other is BSY=1, DRDY=x. This prevents anything from happening
>during spin-up. Unfortunatly, if the pull-down is missing on DB7,
>this can cause the system to think that the channel is empty. I
>believe that the current specification ellows for both
>implementations.
--
---------------------
"Anything you CAN control you MUST control."
Wendy Carlos
---------------------
Larry Barras
Apple Computer Inc.
1 Infinite Loop
MS: 306-2TC
Cupertino, CA 95014
(408) 974-3220
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