ragge@ludd.luth.se wrote:

>Also the later, I ran into a problem where the BI bus were 
>not allowed to do DMA to the XMI space, and I couldn't find 
>out why.  I didn't spend too much time searching for the problem
though.

The only gotcha I recall is that interlocked BI transactions
are not allowed when the BI is hanging off an XMI which is
hanging off another bus (which can only mean an LSB, I think).

So the DSB32 is not supported in a VAX 7000 (because the DSB32
microcode uses interlocked BI transactions) but the DMB32 is
supported (because it doesn't). [I think I have DSB and DMB
the right way round there ...]

I don't recall any DMA limitations.

There's always the XPA/XVA stuff to be aware of with 
VAX 6600/VAX 7000 and XBI+.

Antonio


 --  

Antonio carlini
arcarlini@iee.org