[Info-vax] QIO Writes to a mailbox

[Bob Koehler]

In article <4eb58498$0$19708$c3e8da3$c8b7d2e6 at news.astraweb.com>, JF Mezei <jfmezei.spamnot at vaxination.ca> writes:
> Jim Duff wrote:
> 
>> 
>> Remind me not to hire you as a programmer, as QIO vs QIOW sure does make
>> a difference.
> 
> I am asking in the specific case of the mailbox driver which is an
> in-memory construct and the driver does not have to wait for some device
> to rotate to a specific location before the write can be made, or send
> the data out at low speed over a 110baud line.


   Never the less, it does have to wait for the I/O request packet (IRP)
   to be pulled out of the IRP queue by the driver's start I/O routine,
   which is asynchronous to user mode code.