skyx 写了：猛将兄 写了：这个我就不清楚了，虽然小霸王上的Gbasic也可以定义浮点数，但是不是用FPU算的，我就不知道了。
整数运算单元是必备的。计算机系统就是以整数运算单元为基础的。但FPU不一定
当年286和386都没有集成FPU，是一个选项。287和387就是FPU了
传说中的80x87协处理器？
最早FPU是分离于CPU之外的。虽然我学汇编的时候，已经奔腾时代了，但是我们学校的机器还是286和386，这些也都是学的
Add-on FPUs
Main article: Coprocessor
In the 1980s, it was common in IBM PC/compatible microcomputers for the FPU to be entirely separate from the CPU, and typically sold as an optional add-on. It would only be purchased if needed to speed up or enable math-intensive programs.
The IBM PC, XT, and most compatibles based on the 8088 or 8086 had a socket for the optional 8087 coprocessor. The AT and 80286-based systems were generally socketed for the 80287, and 80386/80386SX based machines for the 80387 and 80387SX respectively, although early ones were socketed for the 80287, since the 80387 did not exist yet.
Starting with the 80486, in x86 chips the floating point unit was integrated with the CPU, something true for almost all later x86-architecture processors. One notable exception is the 80486SX; it was also unusual in that no actual coprocessor was available -- the 80487 was a full CPU with an integrated FPU; when installed, the original 80486SX would be disabled.
In addition to the Intel x87 series, several other companies manufactured co-processors for the x86 series. These included Cyrix which marketed its FasMath series as higher performance but fully x87 compatible, and Weitek which offered a high-performance but not fully x87 compatible series of coprocessors.
In addition to the Intel architectures, FPUs as coprocessors were available for the Motorola 680x0 line. These FPUS, the 68881 and 68882, were common in 68020/68030-based workstations like the Sun 3 series. They were also commonly added to higher-end models of Apple Macintosh and Commodore Amiga series, but unlike IBM PC-compatible systems, sockets for adding the coprocessor were not as common in lower end systems. With the 68040, Motorola integrated the FPU and CPU, but like the x86 series, a lower cost 68LC040 without an integrated FPU was also available.
