The Transmitter section accepts bi-phase TTL data at the input and when coupled to the data bus with a 1:2.5 transformer, isolated on the data bus side with two 52.5 Ohm fault isolation resistors, and loaded by two 70 Ohm terminations plus additional receivers, the data bus signal produced is 7.5Volts nominal P-P at A-A'. (See Figure 5.) When both DATA and DATA inputs are held low or high, the transmitter output becomes