In 1980, self-interpretive EKG machines were not quite yet invented. In their place was a system to capture the EKG in real-time and send to a mainframe computer. If you thnk you have it tough today connecting an AD620 to an Arduino, consider what it took to capture and send a 12 lead EKG in 1980.
First, the be fair, we are talking about a full 12 lead EKG, not the little single lead of EKG you get from an Apple watch or eKardia devices. (see what is a 12-lead EKG/ECG?) In addition as this 12 lead ECG is for a patient and being routed, there is a nine-digit ‘PID’ or patient identification digit.