Intel 8087 浮点芯片的加法器核心
1980 年发布的 Intel 8087 浮点协处理器可将数学运算速度提升多达 100 倍，其核心依赖一个 69 位加法器。本文详细解读了该加法器的电路设计：采用曼彻斯特进位链配合进位跳过（carry-skip）技术，将加法运算拆分为 4 位块来优化性能。文章还分析了 NMOS 晶体管实现的预充电机制、进位传播逻辑，以及加法器在芯片上的物理布局，展示了在晶体管数量受限的 8087 芯片上，如何在复杂度和性能之间取得平衡。
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