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The scanning method is described below with the aid of Figure 1.3. As the figure clearly illustrates, the keyboard consists of an 8 x 8 matrix, the interconnection of each row and column bridged by a normally open switch contact. The row inputs and column outputs are shown connected to separate ribbon cables SK6 and SK7, the column inputs to the CPU's high order address lines CA15 - CA8 and the row outputs to the gate array and CPU on the data bus CDH to CDA (D7 - DO).
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