The size of the ROM required to build an 8-bit adder/subtracter with mode control, carry input, carry output and two's complement overflow output is given as :
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Correct answer: (B) 2¹⁸ × 10
Explanation
Total inputs to the ROM = 8 + 8 (two 8-bit numbers) + 1 (mode) + 1 (carry in) = 18, so the ROM has 2¹⁸ words. Outputs = 8 result bits + 1 carry out + 1 overflow = 10 bits. Hence the ROM size is 2¹⁸ × 10.