X = A(B + C + D) + BCD = AB + AC + AD + BCD
两次取反, 应用德摩根定律
X = ~ ( ~(AB + AC + AD + BCD))
= ~ ( ~AB * ~ AC * ~AD * ~BCD)
= nand ( nand (A, B), nand (A, C), nand (A, D), nand (B, C, D) )
X = A(B + C + D) + BCD = AB + AC + AD + BCD
两次取反, 应用德摩根定律
X = ~ ( ~(AB + AC + AD + BCD))
= ~ ( ~AB * ~ AC * ~AD * ~BCD)
= nand ( nand (A, B), nand (A, C), nand (A, D), nand (B, C, D) )