SAT TEST UNIT READY command translation

Pat LaVarre p.lavarre at
Fri Aug 12 23:17:47 PDT 2005

* From the T10 Reflector (t10 at, posted by:
* Pat LaVarre <p.lavarre at>
> ... closely related START STOP UNIT command.
> SAT revision 5 ties the implementations of those two commands
> together, so perhaps Mark Evan's proposal to change
> the START STOP UNIT command in SAT could be extended to
> cover the TEST UNIT READY command ...

This rings a bell ...

There was some history of substituting one for the other ...

Must have been Start Unit for Test Unit Ready.  The availability of 
that substitution let the host choose whether to see read-protect as a 
test unit ready failure or not.  Send op x00 Test Unit Ready, and then 
read-protect is an error.  Send op x1B Start Unit, and then 
read-protect is not an error.

Nearby in this space was the Microsoft ATA Get Media Status, which saw 
write-protect as an error, even in contexts when errors appeared to 
complete an ATAPI Seek Immediate ...

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