> the results of an MTPR/MFPR on the register are 
> UNPREDICTABLE if memory management is enabled."
>
> So, try to understand what the TBDATA is good for :-)
>
> Note that TBDATA only exists on some very old machines.
>
> Why are you asking about this? :-)

Because I could not bring out the VAX books when I left the previous
employer.  Seriously, I noticed the design similarity (at least in
concept) between VAX and MIPS. 

Tohru Nishimura