39 s are open collector junctions they are connected to plus 30 volts as shown in fig1 noting the interconnections to circuit 10 01 when the line is not addressed the specific output is in an off state the base of the attached transistor is at a plus 30 volt potential and the emitter will be approximately plus 29 volts when the line is addressed the particular sn745n will turn on a specific line the base of the transistor is grounded consequently the emitter will be at drive ground potential since the substrate of the lcd is set at plus 29 volts the ground going pulse will appear to be minus 29 volts with respect to the lcd and the lcd will turn on for this line and display the line of information coming from d a converter 13 0 there are a total of 14 chips of the sn7445n for addressing 100 lines they are sequentially enabled by a logical zero from circuit 10 7 a 74 154 chip it is a logical zero at the most significant bit input to the respective 7445n chips which in essence selects the first eight outputs that are being used when a particular decoder 10 1 10 14 is enabled the sequencing is provided by the counters 10 1 and 10 2 each being a 74 193 chip the counters will advance one state when an inverted line select counter clock occurs the least significant bit to each of the 7445 chips alternatively can be set to a logical one per every other field this condition is assured by circuit 10 3 when it is appropriately actuated via its two inputs a and b thus the least.