TRANSISTOR CIRCUITRY IN THE LINCOLN TX-2 99

On the basis of previous experience, we decided that the advantages of having one standard flip-flop were worth some complication in TX-2 circuitry. The circuit diagram of the flip- flop package in Figure 8 is basically an Eccles-Jordan trigger circuit with a 3-transistor amplifier on each output. The input amplifiers isolate the pulse input circuits and give high-input impedance. The amplifiers give enough delay to allow the flip-flop to be set at the same time that it is being sensed. Figure 9 shows the waveforms of this flip-flop package when complemented at a l0-megapulse rate. The rise and fall times, about 25 millimicroseconds, are faster than one normally sees in a single inverter or an emitter follower because on each output there is an inverter that pulls to ground and an emitter follower that pulls to -3 V. Figure 10 is a plot of the pulse amplitude necessary to complement the flip-flop at various frequencies. Note the independence of trigger sensitivity to pulse repetition rate. This circuit will operate at a 10- megapulse rate, twice the maximum rate at which it will be used in TX-2.

The TX-2 circuits reproduced most often were designed with a minimum number of components to achieve economies in manufacture and maintenance. The design of less frequently reproduced circuits made liberal use of components - even redundancy - to achieve long life and broad tolerance to component variations. The goal was system simplicity and high performance with a lower total number of components than might otherwise be possible. For