Program stores also contained permanent data, and could not be written online. Instead, the aluminum memory cards, also called twistor planes, had to be removed in groups of 128 so their permanent magnets could be written offline by a motorized writer, an improvement over the non motorized single card writer used in Project Nike. All memory frames, all busses, and all software and data were fully dual modular redundant. The dual CCs operated in lockstep and the detection of a mismatch triggered an automatic sequencer to change the combination of CC, busses and memory modules until a configuration was reached that could pass a sanity check. Busses were twisted pairs, one pair for each address, data or control bit, connected at the CC and at each store frame by coupling transformers, and ending in terminating resistors at the last frame.