It seems that the development of [TTL](https://en.wikipedia.org/wiki/Transistor%E2%80%93transistor_logic) was contemporary ~1961 the maiden moon landing of the Apollo vehicle, while the development of one of the oldest digital signalling standards [RS232](https://en.wikipedia.org/wiki/RS-232#History) using the [UART](https://en.wikipedia.org/wiki/Universal_asynchronous_receiver-transmitter#History) hardware was crystallized later, and that of the advent of the [USB](https://en.wikipedia.org/wiki/USB#History) hardware, transmission standard and related communication protocols occurred much later.

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> What was the communication protocol used on the controllers and processers on board the Apollo lander vehicle?
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