| ▲ | snarfy 2 hours ago | |
Which math copro? If you had a 386DX then I believe you had the math copro? The 386SX did not have an FPU and needed the additional 387SX. | ||
| ▲ | dragonwriter an hour ago | parent | next [-] | |
> If you had a 386DX then I believe you had the math copro? The 386SX did not have an FPU and needed the additional 387SX. The 386DX/386SX distinction was the external databus (32-bit on the DX, 16-bit on the SX) DX was “Double word eXternal", SX was “Single word eXternal”. Neither had an FPU builtin, and there were corresponding 387DX and 387SX coprocessors. Then Intel used the same naming split (despite the abbreviations not applying) for high-end vs low-end of the 486 where the DX had a builtin FPU and the SX required a “487SX coprocessor” to get an FPU (which IIRC was internally just a 486DX processor which went into a separate “coprocessor slot” which just bypassed the “main” processor when populated.) | ||
| ▲ | to11mtm 2 hours ago | parent | prev [-] | |
> If you had a 386DX then I believe you had the math copro? The 386SX did not have an FPU and needed the additional 387SX. Neither had FPUs... Closest you can get is RapidCAD (which is really a 486DX adapted to 386 bus, IIRC it uses a 'jumper' for the 387 slot.) For 386, the difference between SX and DX was whether it was a 16 or 32 bit data bus. Where things can get more curious, is that some early 386 motherboards actually took a 287 instead of a 387... | ||