为啥AMD可以用Intel的指令集

这事和IBM有关。Intel had introduced the first x86 microprocessors in 1978. In 1981, IBM created its PC, and wanted Intel's x86 processors, but only under the condition that Intel also provide a second-source manufacturer for its patented x86 microprocessors. Intel and AMD entered into a 10-year technology exchange agreement, first signed in October 1981 and formally executed in February 1982. The terms of the agreement were that each company could acquire the right to become a second-source manufacturer of semiconductor products developed by the other; that is, each party could "earn" the right to manufacture and sell a product developed by the other, if agreed to, by exchanging the manufacturing rights to a product of equivalent technical complexity. The technical information and licenses needed to make and sell a part would be exchanged for a royalty to the developing company. The 1982 agreement also extended the 1976 AMD–Intel cross-licensing agreement through 1995. The agreement included the right to invoke arbitration of disagreements, and after five years the right of either party to end the agreement with one year's notice. The main result of the 1982 agreement was that AMD became a second-source manufacturer of Intel's x86 microprocessors and related chips, and Intel provided AMD with database tapes for its 8086, 80186, and 80286 chips. However, in the event of a bankruptcy or takeover of AMD, the cross-licensing agreement would be effectively cancelled.

IBM was founded in 1911 in Endicott, New York, as the Computing-Tabulating-Recording Company (CTR) and was renamed "International Business Machines" in 1924. In 1969, the United States of America alleged that IBM violated the Sherman Antitrust Act by monopolizing or attempting to monopolize the general-purpose electronic digital computer system market, specifically computers designed primarily for business, and subsequently alleged that IBM violated the antitrust laws in IBM's actions directed against leasing companies and plug-compatible peripheral manufacturers. 1970年时的IBM占到了股市总市值的7%。1999年后微软的市值超过了IBM。

IBM为啥不自己造CPU? 可能: 1. 会被反垄断法制裁; 2. 大公司做事慢花钱多; 3. 不是业务主力试试水。
IBM为啥要second-source manufacturer: 1. Intel弟弟供货能力行吗？2. 不要脾气长得比本事快哦。:-)

AMD被Intel的光芒遮盖，以至于曾有国内媒体把它当成了ADM(Archer Daniels Midland, a food-processing company)，有了"农企"的绰号，其实它也历史悠久，技术雄厚。再说农企咋啦？我对互联网企业有偏见：他们进口芯片，干的是帮助卖土豆换芯片的事。老干妈和马应龙进口啥了？它们纯纯地挣外汇。国产ToneWinner功放国外好评如潮，好像也不用进口太多。买个骁龙999不如雇个打手。不打游戏最好，滑雪真的挺好玩，轮滑也不错。两个糙快猛的例子：B客园主页推荐的帖子，1) 数据库里把172这样以厘米为单位的身高用int来存，但查身高17x时看字符串的前两位是不是"17"，而不是>169 && <180; 2) 从数据库里查东西不用limit, 十几万条记录都拿出来再来个O(n²). 然后抱怨CPU慢再买新服务器？你说啥人不爱听，人是互联网兄贵，钱多、认识的领军人物多。

AMD (Advanced Micro Devices) was formally incorporated by Jerry Sanders, along with seven of his colleagues from Fairchild Semiconductor, on May 1, 1969. Robert Noyce, who had developed the first silicon integrated circuit at Fairchild in 1959, had left Fairchild together with Gordon Moore and founded the semiconductor company Intel in July 1968. 比Intel晚成立1年，创始人也来自仙童半导体。

In November 1969, the company manufactured its first product: the Am9300, a 4-bit MSI (中规模) shift register, which began selling in 1970. Also in 1970, AMD produced its first proprietary product, the Am2501 logic counter, which was highly successful. Its best-selling product in 1971 was the Am2505, the fastest multiplier available. In 1971, AMD entered the RAM chip market, beginning with the Am3101, a 64-bit bipolar RAM. That year AMD also greatly increased the sales volume of its linear integrated circuits, and by year-end the company's total annual sales reached US$4.6 million. AMD went public in September 1972. Total sales in fiscal year 1978 topped $100 million, and in 1979, AMD debuted on the New York Stock Exchange.

When Intel began installing microcode in its microprocessors in 1976, it entered into a cross-licensing agreement with AMD, which was granted a copyright license to the microcode in its microprocessors and peripherals, effective October 1976. 当时AMD的微码技术可能比Intel的先进，请往后看。

不过，Intel had created the first microprocessor, its 4-bit 4004, in 1971. By 1975, AMD entered the microprocessor market with the Am9080, a reverse-engineered clone of the Intel 8080, and the Am2900 bit-slice microprocessor family. AMD最初也做逆向工程。

啥叫bit-slice位切片？There may also be a memory address register and a memory data register, used to access the main computer storage. Even simple computers usually have one unit to read and write memory, and another to execute user code. These elements could often be brought together as a single chip. This chip comes in a fixed width that would form a "slice" through the execution unit. These are known as "bit slice" chips. The AMD Am2900 family is one of the best known examples of bit slice elements. The parts of the execution units and the execution units themselves are interconnected by a bundle of wires called a bus. Microcode can be characterized as horizontal or vertical, referring primarily to whether each microinstruction controls CPU elements with little or no decoding (horizontal microcode) or requires extensive decoding by combinatorial logic before doing so (vertical microcode). Consequently, each horizontal microinstruction is wider (contains more bits) and occupies more storage space than a vertical microinstruction. 这段话我没看懂，重点: The AMD Am2900 family is one of the best known examples of bit slice elements.

比如C代码里: int ary[1000]; return ary[i]; 对应的汇编指令(中的一句)是：mov eax,[ebx]，即ebx里装的内存地址，其机器码是8B 03。CPU处理的是二进制数而不是字符串，要译码(decode)和执行。译码就是知道8B要干啥，9C又要干啥；执行就是具体地去干。

Some hardware vendors, especially IBM, use the term microcode as a synonym for firmware. In that way, all code within a device is termed microcode regardless of it being microcode or machine code; for example, hard disk drives are said to have their microcode updated, though they typically contain both microcode and firmware. SSD有主控芯片。主控so复杂that不是用一个组合电路实现，而是也有CPU，有CPU就有微码。firmware像我们写的.exe。可以说SSD本身就是个电脑。笔记本电脑通过屏幕、键盘、网卡等与外界交流，SSD通过总线与笔记本电脑交流。

• SSI small-scale integration 1964 1 to 10个晶体管 1 to 12个门
• MSI medium-scale integration 1968 10 to 500 13 to 99
• LSI large-scale integration 1971 500 to 20000 100 to 9999
• VLSI very large-scale integration 1980 20000 to 1000000 10000 to 99999
• ULSI ultra-large-scale integration 1984 1000000 and more 100000 and more

By mid-1985, the microchip market experienced a severe downturn, mainly due to long-term aggressive trade practices (dumping) from Japan, but also due to a crowded and non-innovative chip market in the United States. AMD rode out the mid-1980s crisis by aggressively innovating and modernizing, devising the Liberty Chip program of designing and manufacturing one new chip or chipset per week for 52 weeks in fiscal year 1986, and by heavily lobbying [院外游说] the U.S. government until sanctions [禁令] and restrictions were put in place to prevent predatory Japanese pricing. During this time, AMD withdrew from the DRAM market, and made some headway into the CMOS market, which it had lagged in entering, having focused instead on bipolar chips.

历史是相似的，又是不相似的。:-) 比如人均2~3台电脑，对于办公打字已经够快；虽然新电脑更快，为啥要再买？人口红利期过了就多生，始作俑者，其多生乎？