RANDOM_NUMBER_GENERATOR

Published:2009/7/14 3:30:00 Author:May | From:SeekIC

The 74574 flip-flops shown in the circuit are arranged to form a 4-bit shift register. Binary data enter the D0 input on U1-a and are sequentially shifted to each output (Q0, Q1, Q2, Q3) with each clock pulse. The data input to the shift register come from the output of U3-a, one gate of a 7486.That exclusive-OR gate compares two of the output bits from the shift register. If the two bits are the same, then the output of U3-a is 0 Y (or low). If the two bits are different, then the output of U3-a is +5 V (or high). Therefore, U3-a acts as a type of logical-feedback network that changes the data at D0, which, in turn, changes the outputs of the flip-flops. The effect of that network is to create a pseudo-random sequence of bits at the outputs of U1 and U2.



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