2016年7月11日 · Weitek 4167 is a dedicated 487 FPU. Only early 486 boards have a socket for it. It was way faster than integrated 486DX. But software has to support it. Later when DX2 were released the 4167 was obsolete. Comparison 486DX vs 4167: https://www.youtube.com/watch?v=7w-ZCrvxBek

2018年4月4日 · A 486 could be made as a 486DX with a CPU and FPU, 486SX (CPU only) or 487 (FPU). 486DX chips that only passed 1 of the 2 tests could be sold as 486SX or 487.

Because the Cyrix Cx486SLC/DLC CPUs didn't come with an internal FPU (floating-point unit), motherboards that supported these Cyrix CPUs sometimes also provided a Cyrix math coprocessor socket. These were designed to accommodate the 487DLC coprocessor.

Released in the early 1990s as a math coprocessor for personal computers, the Intel 487SX provided the missing floating-point unit (FPU) for the 486SX microprocessor. In actuality, the 487SX is a version of the much more expensive and functional Intel 486DX processor outfitted with an extra pin so that it fits into the coprocessor socket.

To distinguish a 287 and a 387 FPU, you can try if it can see the difference between +infinity and -infinity. FPU control. If an FPU is found to be present, you should set up the control registers accordingly. If an FPU is not present, you should also set up the registers accordingly. CR0.EM (bit 2; counting starts at bit 0 making this the ...

2005年1月12日 · 487SX是为486SX升级设计的，但它不是FPU。 把它插在主板上，486SX就不工作，完全由487SX接替工作。 它具有486DX的所有功能。 所以它是CPU而不是FPU。 至少它在某些主板上可以独立工作。 刚拍的它在独立工作的图。 图一是在主板上的照片，图二是屏幕上显示的CPU是487SX，图三是主板跳线说明，可以支持487SX。 487它并不能单独作为CPU使用，而是要依靠486SX,在任何一张主板中，只要有487，就一定有486SX，但有486SX，不一定有487 …

2015年11月28日 · A 487 is a 486 that fits into the 'FPU' socket of a 486SX board. They all have the same ALU. He probably meant something like using an SX2 or a 486-class processor from another maker with poor FPU performance, then use …

2018年12月6日 · There is a signal sent from the 487 that shuts down the 486SX or 486DX. The dual FPU issue can occur. I have a motherboard (486SLC) with soldered in 387 and a Weitek socket. I never tried inserting a Weitek chip to see how it decides between the two FPUs. You can try it yourself but IIRC, only the 487 in the 487 socket will do anything.

2016年12月15日 · While there might not be some major difference between 387 and 487 part in DX cpu, there are major differences with CPU-FPU communication. In 486DX fpu instructions execute in a single cycle, while on 386/387 combo they take several (3-5) and take big performance hit.

2010年8月22日 · 80487SX 的確就等於 80486DX ... 多一根腳... 那根腳的用途很簡單, 就是要讓 486SX 不動作... Weitek 1167/3167 搭配在 80386 上, 但運作原理跟 x87 不同, 跑的當然也不是 x87 的指令集... 要 compiler 有特別支援, 產生相對應的程式碼... 它的設計方式, 其實很簡單... 全部都透過 CPU 下 memory 讀寫動作來運作... (在當年這樣的設計會比外掛的 x87 co-processor 快...) 32-bit data 則是看指令格式, 傳送或是得到相對應的參數或結果資料... 樓主我想問一下, 有幾張NEC …