{"resolved":true,"match_type":"uuid","source_type":"original_book","book_id":"38270854-596f-4a26-8183-db8c968c6020","title":"编码 隐匿在计算机软硬件背后的语言","author":null,"edition":null,"publisher":null,"year":null,"isbn":"9787121181184","requested_by":"printed_page","book":{"source_type":"original_book","book_id":"38270854-596f-4a26-8183-db8c968c6020","id":"38270854-596f-4a26-8183-db8c968c6020","uuid":"38270854-596f-4a26-8183-db8c968c6020","title":"编码 隐匿在计算机软硬件背后的语言","normalized_title":"编码隐匿在计算机软硬件背后的语言","author":null,"edition":null,"publisher":null,"year":null,"isbn":"9787121181184","isbns":["9787121181184","0123456789","6044921875","3039331000","0000000000","0000000000000"],"parsed":true,"ai_readable":true,"document_type":"book","page_count":438,"navigation_url":"https://workshop.closeclaw.top/ai/book/38270854-596f-4a26-8183-db8c968c6020","title_url":"https://workshop.closeclaw.top/ai/title/%E7%BC%96%E7%A0%81%20%E9%9A%90%E5%8C%BF%E5%9C%A8%E8%AE%A1%E7%AE%97%E6%9C%BA%E8%BD%AF%E7%A1%AC%E4%BB%B6%E8%83%8C%E5%90%8E%E7%9A%84%E8%AF%AD%E8%A8%80","fixed_page_url_template":"https://workshop.closeclaw.top/ai/book/38270854-596f-4a26-8183-db8c968c6020/page/{printed_page}","path_api_url_template":"https://workshop.closeclaw.top/api/ai/book/38270854-596f-4a26-8183-db8c968c6020/page/{printed_page}","read_url":"https://workshop.closeclaw.top/api/ai/read/38270854-596f-4a26-8183-db8c968c6020","page_url":"https://workshop.closeclaw.top/api/ai/books/38270854-596f-4a26-8183-db8c968c6020/page","search_url":"https://workshop.closeclaw.top/api/ai/books/38270854-596f-4a26-8183-db8c968c6020/search"},"page":{"printed_page":155,"pdf_page":171,"physical_index":171,"physical_index_base":0,"printed_page_status":"recognized","page_sha256":"f22bdd7765cf87d17557f8a115a2e56b7182757b52e892cb2be9e7b38077401a"},"chapter":"编码隐匿在计算机软硬件背后的语言","content":"将8个异或门合并起来画成一个器件，称为求补器（One's Complement)，如下所示。\n\n将一个求补器，一个8位二进制加法器和一个异或门做如下连接。\n\n注意，这里三个信号都标识为“SUB”，这就是加/减法转换开关。当该信号为0的时候，其进行的是加法运算，为1时进行的则是减法运算。在减法中，输入B(第二排开关）在送入加法器之前，需先通过求补电路进行取反。此外，在做减法时，我们通过设定CI（进位输入）为1来使得结果加1。而在加法中，求补电路将不起作用，且输入CI为0。\n\n加法器的 SUB信号和CO（进位输出）输出作为异或门的输入来控制表示上溢/下溢的灯泡。如果SUB信号为0（表示进行加法运算)，则当加法器CO输出为1时灯亮，意思是加法计算结果大于255。\n\n当进行减法运算的时候，如果减数（输入B）小于被减数（输入A），这时加法器的\n\n13 如何实现减法\n\n155","previous_page":154,"next_page":156}