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Wang LOCI-2 Circuit Board 1402A

The 1402A board primarily contains the 40 flip-flop storage elements that make up the ten digits of the W (Working) register. Each digit in the register is represented by four flip-flops which contain a Binary-Coded Decimal representation of the digit. The flip-flops are arranged as a shift-register so that numbers can be shift into and out of the register. Also included on the 1402A circuit board is a four-bit parallel binary coded decimal adder that is used for performing addition and subtraction, as well as used during the logarithm and anti-logarithm generation operations. Various other logic also resides on this circuit board, including a circuit to detect if addition or subtraction results in an overflow, including the "Error" flip-flop, and a number of other status flip-flops and logic is used to generate control signals that are used by other sections of the calculator.