4 ms·
> such as the (in)famous evaluate polynomial instruction, POLY. What CPU has this instruction and where can I learn more about it?
by Carioca 3y ago
> such as the (in)famous evaluate polynomial instruction, POLY.
What CPU has this instruction and where can I learn more about it?
- cmg 3y agoLooks like a VAX 11 thing: https://documentation.help/VAX11/op_POLY.htm https://documentation.help/VAX11/op_POLY.htm See also http://simh.trailing-edge.com/docs/vax_poly.pdf# http://simh.trailing-edge.com/docs/vax_poly.pdf# and some HN discussion from 2015: http://simh.trailing-edge.com/docs/vax_poly.pdf# http://simh.trailing-edge.com/docs/vax_poly.pdf#
- nxobject 3y agoMy other favorite instructions on the VAX: the CRC instruction, the CASE dispatch table operations, and, glory of all glories, the _3-parameter_ operand + operand + destination instructions.
- jakey_bakey 3y agoFrankly, I tried to go into depth on this because it was really interesting. I am embarrassed to say it was tough to find sources outside Quora and Reddit. It's possible this HackerNews comment parent might become the canonical source :)
- Carioca 3y agoThere are a few answers to my question now, if you're still curious
- clausecker 3y agoThis one is as infamous as it is useful. Modern CPUs have the same instruction, but without the built-in loop (fused multiply-add). Likewise, modern CPUs have dedicated CRC instructions, ARM Thumb 2 famously has an instruction for case statements (jump tables, instructions TBB/TBH), and many more. The VAX was way ahead of its time, but failed to deliver on performance due to not having a pipelined or out-of-order architecture as is industry standard today.