29 June 1965: Communication Instructions HYDRA Service Procedures (HSP 101)

Not only was there a “hardware” change to HYDRA, there was a corresponding “software” change to HYDRA with the introduction of STRAD. This memorandum outlines the new HYDRA service procedures – the instructions an operator would feed into the device in order to send, receive, and route messages. Annex B contains a lengthy list of “traps” that an “unwary or unfortunate operator” might fall into when trying to work within the STRAD. Users are reminded that “STRAD is a machine. It does not make mistakes itself but cannot correct errors made by you.”