def start_program(linker = nil)
      initialize(linker || @linker)
      init = @linker.cpu_init
      set_state(:running)
      set_pc( Position.get(init).at )
    end
def start_program(linker = nil)
      initialize(linker || @linker)
      init = @linker.cpu_init
      set_state(:running)
      set_pc( Position.get(init).at )
    end
somewhat like the lags on a cpu, hash  sym => bool (zero .. . )
start in state :stopped and set registers to unknown