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Intel 80386, a Revolutionary CPU

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Re: Intel 80386, a Revolutionary CPU

#11
post #2

How different are the instruction sets of the 80486 and Pentium from the 386? Put another way, had the instruction set been frozen as of the 386 (barring any required changes for 64-bit), would we notice any difference in performance today?

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Re: Intel 80386, a Revolutionary CPU

#12

They were in big trouble then. The entire company was riding on it being great. It could have easily gone awry as it did for Data General, Honeywell, CDC, AST, Tandy, Olivetti, Xerox, DEC Rainbow, AT&T Hobbit, Wang 2200 and Unisys. Strong survivorship bias on this one. Most of the once Titans are in or near the dustbin now, such as SDS, SDC and Fairchild. Intel's history was primarily as a memory manufacturer. They'r…

Andy Grove moving Intel from memory to microprocessors was an excellent strategic move.

> "Business success contains the seeds of its own destruction. Success breeds complacency. Complacency breeds failure. Only the paranoid survive."

Something that Intel's leaders didn't pay attention to during the 2010s.

Re: Intel 80386, a Revolutionary CPU

#13
post #8

They were in big trouble then. The entire company was riding on it being great. It could have easily gone awry as it did for Data General, Honeywell, CDC, AST, Tandy, Olivetti, Xerox, DEC Rainbow, AT&T Hobbit, Wang 2200 and Unisys. Strong survivorship bias on this one. Most of the once Titans are in or near the dustbin now, such as SDS, SDC and Fairchild. Intel's history was primarily as a memory manufacturer. They'r…

What’s their hope right now? Some sort of Quark-derived desktop CPU à la Dothan?

Doubling down on becoming a competitive foundry and becoming the western equivalent to TSMC. If their 18A process ships on time (2025), there's a chance that they could regain process leadership.

Re: Intel 80386, a Revolutionary CPU

#14
post #5
post #2

How different are the instruction sets of the 80486 and Pentium from the 386? Put another way, had the instruction set been frozen as of the 386 (barring any required changes for 64-bit), would we notice any difference in performance today?

Vector instructions are the obvious thing and being massive gains to media, cryptography, math, AI, graphics, and signal processing. Beyond that there have been a few additions like CMOV (conditional move) that would be missed, though instruction fusion in pipelines can sometimes achieve the same speed up. Lastly you would have to add some atomic instructions to support SMP.

CMOV is very important for high-performance programming as it greatly simplifies the design of branchless code. There are workarounds, but they either involve conditional branches (you don't want these) or increase the critical path latency significantly (the simplest workaround is to materialise the carry flag using SBB, then use that as a mask).

Re: Intel 80386, a Revolutionary CPU

#16
post #8

They were in big trouble then. The entire company was riding on it being great. It could have easily gone awry as it did for Data General, Honeywell, CDC, AST, Tandy, Olivetti, Xerox, DEC Rainbow, AT&T Hobbit, Wang 2200 and Unisys. Strong survivorship bias on this one. Most of the once Titans are in or near the dustbin now, such as SDS, SDC and Fairchild. Intel's history was primarily as a memory manufacturer. They'r…

What’s their hope right now? Some sort of Quark-derived desktop CPU à la Dothan?

Coming out with better chips at lower prices. I know how obvious that sounds but it's true.

The difficulty is they need to make nearly decade-long bets that are the size of small countries economies due to the complexity of manufacturing and Intel's made a few bad ones recently.

I don't know who to listen to on what chip design will be a market win in 2030 either. AI applications are extremely resource intensive so that will be driving things for a while but how to solve that in an affordable chip created by a reliable efficient manufacturing process is beyond me. This stuff is phenomenally hard.

I'd say the winner is something like an NVIDIA graphics pipeline that is separated into a pile called "graphics" and "ai" and then has the graphics part gutted for a cheaper AI pipeline which can use system memory as opposed to preciously expensive graphics memory and then gets integrated into their next gen CPUs taking Nvidia out of the loop and dealing a blow to AMD at the same time. They'd mop the floors with something like that especially if you could just drop it into pytorch and have it work automagically. They could probably then just turn around and license it to ARM.

AMD and Nvidia wouldn't work together to mount a unified defense because of ATI and this would allow Intel to weasel their way back into the Apple money stream.

But I'm just some unemployed dude typing this on a 4 year old android. Don't listen to me.

Re: Intel 80386, a Revolutionary CPU

#17
post #2

How different are the instruction sets of the 80486 and Pentium from the 386? Put another way, had the instruction set been frozen as of the 386 (barring any required changes for 64-bit), would we notice any difference in performance today?

Even besides new instructions the 486 and then Pentium ran existing x86 code faster than the 386 clock for clock. Various new instructions did add capability but just running existing code faster was a huge win on subsequent chips.

Re: Intel 80386, a Revolutionary CPU

#18
Maybe just me, but this sounds pretty revisionist wrt 'most important'. If the 8086/8088 hadn't stumbled into ubiquity via the IBM PC, there probably never would have been an 80286 much less an 80386. YMMV.

That said...the 386 was a world-changing engineering achievement, and as much as I think in a just and fair timeline the 68030 would have taken over the world ( :-) ), you can't discount what Intel did.

Re: Intel 80386, a Revolutionary CPU

#20

I forgot how powerful the i960 was - and how this demonstrated that despite that - that compatibility was king.

The i960 apparently had enough embedded use, e.g. in printers, switches, terminals. That is, where binary compatibility did not matter much.

We under-appreciate how little binary compatibility matters now, so that you can even develop something on an ARM-based machine and then rebuild and safely deploy to an x64-based machine (usually because it's Node, JVM, Python, etc).

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