Hi all:

I found the following about R0 in the architecture specification:


> R0 is used as a constant zero.

That is the basic assumption which everybody counts upon, therefore...


> R0 should never be used as a destination register.

I would add here "except for clearing it on start-up".


> An implementation is not required to initialize GPRs to zero during the reset 
> procedure.

I would add here "except for R0, which must be cleared on start-up".

Otherwise, R0 may not be 0 after all, and that would be a violation of the 
assumption above.


Regards,
  R. Diez
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