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halt: This is an error state in which the CPU will do nothing until reset
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fetch: gets the next instruction from memory
- modifies: PC incremented, stores loaded instruction in IB
- nextstate: usually fetch_a, others for fome special instructions (IAG, RFI, HWN)
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fetch_a: fetches the value for the a argument
- modifies: internal a argument register, NW (NextWord, internal) or SP for some instructions
- nextstate: fetch_b for most, nextword_a if NW is required, others for special instructions
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nextword_a: takes care of the extra memory access using the nextword argument
- modifies: internal a argument register
- nextstate: whatever state fetch_a would have gon to instead of nextword_a
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fetch_b:pretty much the same as fetch_a
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nextword_b: pretty much the same as nextword_a
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set_write: writes from the src to the dest
- modifies: dest location
- nextstate: fetch for SET, inc_ij for STI, dec_ij for STD
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arith_write: writed the value returned by the ALU to dest
- modifies: dest location
- nextstate: fetch
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inc_ij: increases I- and J-Registers by one
- modifies: I and J (GP[6] & GP[7])
- nextstate: fetch