Zero detection

One of the bits in your status register is set when both the outputs of the register file are zero. This is not hard to do - if any bit in either output is 1 then you know both outputs are not zero. However, there is not a component in the library to do this. You can construct one with a wad of OR gates, but that is painful. Thus, if you want to write a behavioral component that takes 2 word inputs and returns 1 if no bit in either word is 1, that's fine. It's a trivial component if you just use a loop to search each 16 bit word for a 1.
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