[Info-vax] yet another sys$qiow question

[John Reagan]

On Wednesday, August 19, 2015 at 7:27:30 PM UTC-4, David Froble wrote:

> 
> Ok, just so dumb me can understand, did you just write that before I'm notified 
> of the completion of a QIO, the IOSB has been updated and ready to read?  I 
> really cannot imagine anything else.  I do understand that prior to that 
> notification that the contents of the IOSB is indeterminate, or worse.
> 

The IOSB is cleared for you by the service (that's in the manual).

As for checking the IOSB, also from the manual for $QIO

The condition value returned in R0 and the condition value returned in the
I/O status block provide information about different aspects of the call to the
$QIO service. The condition value returned in R0 gives you information about
the success or failure of the service call itself; the condition value returned in
the I/O status block gives you information about the success or failure of the
service operation. Therefore, to accurately assess the success or failure of the
call to $QIO, you must first check the condition value returned in R0. If R0
contains a successful value, then you must check the condition value in the
I/O status block.