Agnes en Henk Tobbe wrote:

> Can anyone tell how come? Cannot bits in W be tested?
Nope. W is not a register as all the others. W can be written too and
read from, but cannot be manipulated as with other registers.
W is the working register for the ALU and shouldn't be thought of as an
actual register.

You have to do things like you did in your second example.

Quentin