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The operation of transformer read-only stores is explained and the main methods of construction described. The optimum turns ratio of the transformers is calculated. It is shown how a transformer can produce an output current even though the energised word line is not threaded through it. The value of this zero current depends on the information pattern and is found to be greatest with one of two patterns, depending on the type of construction used. For both patterns, expressions for the maximum zero and minimum ONE output signals are derived. The cause of resonances is explained and a method of damping described. The expressions for optimum turns ratio, maximum zero and minimum one output signals are modified to take account of the damping and a worked example is given. Computed and observed output waveforms are compared for a store containing a non-worst-case pattern and are found to agree well.
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