Currently, an annulled instruction gets turned into a no-op, by convention the all-zero instruction.
We should enable the reverse mapping: if the instruction is a no-op, then raise Annul.
The detector would be a set of all-zero detectors, with the sub-signal of D == 0 used to disable writes to A/B, enforcing the "read-only" behaviour of address 0.
Currently, an annulled instruction gets turned into a no-op, by convention the all-zero instruction.
We should enable the reverse mapping: if the instruction is a no-op, then raise Annul.
The detector would be a set of all-zero detectors, with the sub-signal of D == 0 used to disable writes to A/B, enforcing the "read-only" behaviour of address 0.