POLL: x86 vs ARM vs RISC-V; What is your favourite CPU ISA?

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moinmoin

Diamond Member
Jun 1, 2017
5,094
8,098
136
Compilers still haven't replaced the performance advantage hand coded assembly can give (the abundance of performance just doesn't make people care anymore outside of specialized libraries). Maybe AI (technically big data) after some time can help get closer to that point without making a mess of its own.
 

Schmide

Diamond Member
Mar 7, 2002
5,596
733
126
Although I had experience with 6502, basically a kid typing in examples from magazines, I learned on a VAX. It was a good ISA. Lots of registers and virtualization.

You can basically do everything in C++ that you can in assembly with intrinsics. Compilers are darn good at producing assembly level efficiency. Auto vectorization not as much.

High level languages often fail to compete because of extensive use of encapsulation and static data. (can of worms)
 

Schmide

Diamond Member
Mar 7, 2002
5,596
733
126
Is that the case with Rust too?
Yeah. Rust hasn't been around long enough for the tool chain evolve to the level of GCC/LLVM.

In some ways it's a step in the wrong direction for auto vectorization as it is strongly ordered and typed. I didn't even know you could do instrinsics in rust till I looked it up. (introduced circa 2022)
 

kschendel

Senior member
Aug 1, 2018
275
206
116
Help us understand why DEC VAX assembly was fun and why x86 assembly is depressing. We (or even just I) would like to feel the despair without actually touching the turdy code
The VAX had an instruction for just about everything you wanted to do in assembler: enough registers, a nice variety of looping controls, a reasonably regular instruction set so that you didn't have to remember a manual's worth of exceptions and special cases, and some genuinely goofy instructions for fun (such as INSQUE and REMQUE for queues, and POLY for polynomial evaluation).

x86 is pretty much the opposite, although some of the worst offenses such as the bizarre register set and design were alleviated somewhat with x86_64. There aren't enough registers, the instruction set is lopsided, and I'm not a huge fan of condition code oriented ISA's. It almost feels like programming a 6502 where you had to know what register you were allowed to use for what instruction or addressing mode.

The DEC-10 was the most fun because of the incredibly regular and complete instruction set, along with enough registers to get along with. It's true that one side effect is that the DEC-10 usually had several ways of doing the same thing, but even that could be fun. (The team I worked with once had a contest to see how many ways we could invent to zero a register in a single instruction. I think we got up into the 50's, and even today when I haven't been near a DEC-10 for about 40 years, I can still think of at least 15 easily.)
 

Nothingness

Diamond Member
Jul 3, 2013
3,134
2,145
136
(The team I worked with once had a contest to see how many ways we could invent to zero a register in a single instruction. I think we got up into the 50's, and even today when I haven't been near a DEC-10 for about 40 years, I can still think of at least 15 easily.)
Oh that seems to be a funny contest to have!

Without giving it a thought, I can likely list a dozen of ways to zero a register on AArch64. But that's cheating as there is a register hardwired to zero
 

KompuKare

Golden Member
Jul 28, 2009
1,196
1,506
136
I do wonder from the poll if people have misunderstood the question, or have zero knowledge how bad x86 was in the 80s or 90s?

And that knowledge could have been first hand, or watched from afar.
A common home computing though back then was: keep as far away from PCs as possible! Of course, that wasn't entirely Intel's fault as IBM and Microsoft all contribute too with decisions to put the BIOS and other reserved space above user space and other IBM decisions. And Microsoft with MS-DOS's quirks. The strange and cryptic config.sys and the way interrupts were done.

Even home uses on far cheaper hardware - especially the Commodore Amiga and Atari ST users all using far more elegant Motorola 68k processors with their 32 bit registers - watched with horror and amazement how programmers for the IBM PC & co had to struggle with 16 bit and real and protected modes, use crazy offset programming and split things into 64KB chunks etc.

Intel were very lucky that IBM didn't take personal computer seriously and stumbled into the PC market and choose they infamous Intel and Microsoft combination.

Lucky because with mountains of money the PC and compatible brought in, a design which was a sad joke in 1980 somehow managed to almost totally dominate.

The overhead of x86 history is still there but has largely been abstracted away and it's not a huge overhead anymore.

The poll? More options would have been nice, or at least an anything but x86 option!
 
Jul 27, 2020
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Major off-topic post

^^^ Reminds me that I used to have a DOS programming reference tome that listed the various functions of DOS that application programmers could use. It was totally gibberish to me coz I was just a teenager and didn't even know C at the time. I remember vaguely that calling any function caused the values of one or two or maybe more registers to change and the programmer was supposed to check the register values to decide if the function executed successfully or whatever. Seemed like a real headache.

So the barrier of entry was high when creating applications, utilities and games and only the really determined souls with super sharp minds attempted writing them. That's why I guess I enjoyed using software in that era because the software was pretty polished and DOS didn't crash as much as Win3.1 and the later Windows did until Windows 2000. Computers were pretty silent too and the loudest thing you could hear was seek noise from the HDD in the dead of night. You could have days and weeks of fun with a limited library of games and other entertainment applications. Now there's just too much out there that deciding what to spend time on becomes a waste of time itself. And to think that we got to this point because Gary Kildall didn't give an F about IBM!


In an alternate reality, there is no x86 ISA. The world runs on Motorola processors, Steve Jobs is still alive, Bill Gates is WORKING for Steve Jobs, everyone affectionately calls their computer Lisa, there is no game called Doom, the fps that started it all is called Marathon and made by Bungie, everyone has a Nokia phone, Java is the dominant language used for phone apps, Blackberry tried to take over the world and failed because Canadians are so peaceful that they don't understand the Art of War, Japanese only use NEC computers, PS5 uses the third generation Cell processor, Xbox does not exist, Nintendo consoles are only played by preteens and younger kids, SEGA is the No.2 console maker and played by everyone that can't afford the PS5, Russians and Chinese use Atari computers with BASIC language coz computer scientists in Western universities caught Russian/Chinese students trying to hack university computers so they got the West to ban export of anything more powerful than an Atari for national security reasons, PowerVR is the dominant GPU company, reverse hyperthreading actually works coz Intel is a memory company so they never bought Soft Machines, John Carmack developed his World Engine that is used to create the Matrix, all psychopaths are identified via psychiatric evaluation and plugged into the Matrix where they only harm each other and the world has never been more peaceful.

DAMN YOU, GARY KILDALL FOR EFFING UP THE ENTIRE WORLD!!!!
 
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soresu

Diamond Member
Dec 19, 2014
3,273
2,549
136
Major off-topic post

^^^ Reminds me that I used to have a DOS programming reference tome that listed the various functions of DOS that application programmers could use. It was totally gibberish to me coz I was just a teenager and didn't even know C at the time. I remember vaguely that calling any function caused the values of one or two or maybe more registers to change and the programmer was supposed to check the register values to decide if the function executed successfully or whatever. Seemed like a real headache.

So the barrier of entry was high when creating applications, utilities and games and only the really determined souls with super sharp minds attempted writing them. That's why I guess I enjoyed using software in that era because the software was pretty polished and DOS didn't crash as much as Win3.1 and the later Windows did until Windows 2000. Computers were pretty silent too and the loudest thing you could hear was seek noise from the HDD in the dead of night. You could have days and weeks of fun with a limited library of games and other entertainment applications. Now there's just too much out there that deciding what to spend time on becomes a waste of time itself. And to think that we got to this point because Gary Kildall didn't give an F about IBM!


In an alternate reality, there is no x86 ISA. The world runs on Motorola processors, Steve Jobs is still alive, Bill Gates is WORKING for Steve Jobs, everyone affectionately calls their computer Lisa, there is no game called Doom, the fps that started it all is called Marathon and made by Bungie, everyone has a Nokia phone, Java is the dominant language used for phone apps, Blackberry tried to take over the world and failed because Canadians are so peaceful that they don't understand the Art of War, Japanese only use NEC computers, PS5 uses the third generation Cell processor, Xbox does not exist, Nintendo consoles are only played by preteens and younger kids, SEGA is the No.2 console maker and played by everyone that can't afford the PS5, Russians and Chinese use Atari computers with BASIC language coz computer scientists in Western universities caught Russian/Chinese students trying to hack university computers so they got the West to ban export of anything more powerful than an Atari for national security reasons, PowerVR is the dominant GPU company, reverse hyperthreading actually works coz Intel is a memory company so they never bought Soft Machines, John Carmack developed his World Engine that is used to create the Matrix, all psychopaths are identified via psychiatric evaluation and plugged into the Matrix where they only harm each other and the world has never been more peaceful.

DAMN YOU, GARY KILDALL FOR EFFING UP THE ENTIRE WORLD!!!!
Not a chance.

Once upon a time DEC Alpha was kicking 🍑 and taking names.

In fact it actually pioneered many of the fundamental µArch features of CPUs we have come to take for granted today.

Without x86 as competition they could have absolutely taken over the market.

It's not even a question in my mind whether that could have happened.
 

FlameTail

Diamond Member
Dec 15, 2021
4,094
2,465
106
Recent C&C article that argues that the CISC vs RISC debate needs to die.
An older C&C article about ARM vs x86

 

SarahKerrigan

Senior member
Oct 12, 2014
735
2,035
136
Not a chance.

Once upon a time DEC Alpha was kicking 🍑 and taking names.

In fact it actually pioneered many of the fundamental µArch features of CPUs we have come to take for granted today.

Without x86 as competition they could have absolutely taken over the market.

It's not even a question in my mind whether that could have happened.

There is certainly a doubt in my mind. Alpha sales never accounted for more than 10% of the RISC/UNIX market, where x86 wasn't competition. They were always well behind Power/PPC, PA, and SPARC. In '99, Alpha represented something like 7% of the RISC server market - barely ahead of SGI and the tiny MIPS vendors (NEC, Siemens, etc.)

By the late 90s their perf advantage had evaporated, too - they were pretty much at the same perf level as contemporary PA and not far enough ahead of x86 to justify their drastically higher price.
 

poke01

Platinum Member
Mar 8, 2022
2,347
3,065
106
x86/Intel would have dominated if Intel took that iPhone contract. Also Atom would not be bad. Intel would have been the leader in performance per watt.


That’s a very pretty and sad reality in an alternate universe
 
Jul 27, 2020
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x86/Intel would have dominated if Intel took that iPhone contract.
Intel could still have made it in the Android market if they had a worthy low power SoC. And even if the iPhone x86 had been a success, Apple would still have kicked it to the curb sooner or later with their inhouse SoC. They want to be as much in control of their ecosystem as possible. Absolute control freaks which keeps them from becoming the dominant player in the world of personal computing. Even now, if they were to let existing ARM players license their M1 SoC for use in their own devices with any OS of their choice and keep M2, M3 and all future Mx series to themselves, they could cause quite a dent in the personal computing landscape in terms of efficiency and performance. But they would rather hoard all the advantage for themselves than be a power of good.
 

FlameTail

Diamond Member
Dec 15, 2021
4,094
2,465
106
Even now, if they were to let existing ARM players license their M1 SoC for use in their own devices with any OS of their choice and keep M2, M3 and all future Mx series to themselves, they could cause quite a dent in the personal computing landscape in terms of efficiency and performance.
Their is no need. Snapdragon X Elite is coming.
 
Jul 27, 2020
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Snapdragon X Elite is coming.
But it's the same problem. They won't license their core out (even a nerfed version) to other players to cause a significant performance shift in the general computing experience of the masses. I don't have much hope for WoA until AMD enters the foray.
 

FlameTail

Diamond Member
Dec 15, 2021
4,094
2,465
106
But it's the same problem. They won't license their core out (even a nerfed version) to other players to cause a significant performance shift in the general computing experience of the masses. I don't have much hope for WoA until AMD enters the foray.
How about ARM Cortex X5 (BlackHawk) + Nvidia?
 

poke01

Platinum Member
Mar 8, 2022
2,347
3,065
106
Intel could still have made it in the Android market if they had a worthy low power SoC. And even if the iPhone x86 had been a success, Apple would still have kicked it to the curb sooner or later with their inhouse SoC. They want to be as much in control of their ecosystem as possible. Absolute control freaks which keeps them from becoming the dominant player in the world of personal computing. Even now, if they were to let existing ARM players license their M1 SoC for use in their own devices with any OS of their choice and keep M2, M3 and all future Mx series to themselves, they could cause quite a dent in the personal computing landscape in terms of efficiency and performance. But they would rather hoard all the advantage for themselves than be a power of good.
I mean that’s no different than AMD and Intel being hoarding the x86 licence from others like Nvidia, Qualcomm, MediaTek and Apple.

Intel/AMD don’t want to do that because once they share their x86 license the duopoly shatters.

Similarly, there is no one stopping others from making a M1 like SoC. The Snapdragon X Elite is a souped up M1 and is suited for Windows OEM partners. The M Series I feel like is tailor made for Apple products.
 
Jul 27, 2020
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Intel/AMD don’t want to do that because once they share their x86 license the duopoly shatters.
It's mainly Intel who won't allow that. AMD has no say in the matter since they don't own x86. Maybe they'll show they've gotten tired of Intel's ISA extension games by giving the world their own RISC-V CPU design.
 

soresu

Diamond Member
Dec 19, 2014
3,273
2,549
136
x86/Intel would have dominated if Intel took that iPhone contract. Also Atom would not be bad. Intel would have been the leader in performance per watt.


That’s a very pretty and sad reality in an alternate universe
As far as I am aware ARM have pretty much always been able to keep ahead of Atom in terms of raw IPC, perf and perf/watt.

Certainly the design schedule for Cortex A8 would have significantly preceded Intel turning down Apple, and even with x86's dominance in the PC field there were still numerous places in consumer electronics where RISC held the high ground (including all game consoles prior to OG Xbox, and then XB1/PS4

Those markets were only going to benefit from ARM pushing the performance envelope further, so even without smartphones going ARM they would still have pushed forward, if perhaps not so aggressively.

Who knows what would have happened if x86 took smartphones - maybe ARM might have snagged the XB1/PS4 generation instead of AMD/x86.
 

MadRat

Lifer
Oct 14, 1999
11,950
272
126
How about a philosophical CPU pair of 'cores' sharing the same shared rectangular map of execution units. RISC commands run through from its wide side with a huge register to float massive parallel workloads using narrow pipelines. CISC commands run through from the narrow end using long pipelines...
 
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scannall

Golden Member
Jan 1, 2012
1,960
1,678
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x86/Intel would have dominated if Intel took that iPhone contract. Also Atom would not be bad. Intel would have been the leader in performance per watt.


That’s a very pretty and sad reality in an alternate universe
From what I understand Apple wanted Intel to build an ARM SOC using Intel's Xscale division. Intel later sold that off to Marvell.
 
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