I always thought the 8087 was way cool, but it never really caught on. Early versions of Win32 did not save the 8087 registers on a context switch. I called up some people at Microsoft to please not destroy the 8087, and they relented and preserved the registers.
I've always been proud to support the 8087 with my compilers, and am baffled why the numerics people ignore it.
Kind of shocking that a 1980 chip could do 80 bits floating points. It makes me a little mad at all of those microcontrollers from this year, 46 years later that ship without floating point support or, at best, 32 bits, but they do come with a "secure island" and a radio capable to ring ET.
[delayed]
But they can, it's just not accelerated by hardware built specifically for the task
Gosh thank goodness for Ken, a beacon of light in a sea of slop. For all these years, and countless hours of posts and videos, thank you.
Author here with another 8087 article. What part of the 8087 should I look at next?
There's a ton of coordination lately on P6 microcode. Would love to see what twists and turns there are supporting the older isa on newer architectures
I am curious about the transcendental instructions, how are they implemented, and used, and if actually used
Minor erratum: "1.1 (binary) × 2^8 is 304" should be 384.
Thanks! I guess I didn't have my glasses on when I read that number :-)
righto.com has been great reading. None of my friends wanted to pay for an 8087, but I can still remember getting out of school (for 2nd time) and saving up for the 486DX after 3 others got them. After that, well, it's been quite a ride.
Have you already covered how the decoding of instructions is shared with the 8086?
I describe the 8087 instruction decoding here: https://www.righto.com/2026/02/8087-instruction-decoding.htm...
[flagged]