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Comment on Former Intel CPU engineer details how internal x86-64 efforts were suppressed prior to AMD64's success

es they have, and that’s what the vast majority of people mean when they say a CPU is 32-bit or 64-bit

I have no idea how this is upvoted, because it’s decidedly false.
The most common is to use the DATA-bus as a significant measurement.
But despite that Motorola 68000 was mostly called a 32 bit CPU, because f its 32 bit instruction set, and it was available with 8, 16 and 32 bit databus.
In the same way 80386 was called 32bit, despite the SX only had a 16 bit databus. It had a 24bi address bus.

Show me just ONE example of a CPU that was called by its address bus.

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tekato@lemmy.world ⁨4⁩ ⁨weeks⁩ ago
I guess you know more about hardware nomenclature Linux kernel developers, because they call modern Intel/AMD and ARM CPUs amd64 and aarch64, respectively.

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- Buffalox@lemmy.world ⁨4⁩ ⁨weeks⁩ ago
  AMD64 is the name of the instruction set they program to, it has nothing to do with how many bit the CPU is. Except obviously the core instruction set is 64 bit, but as I’ve tried to explain, a chips bit width is not realistically determined by instruction set alone.
  
  Although they are almost identical, the equivalent Intel is called i64.
  AArch64 Is the Arm Architecture family 64, again the instruction set you program for.
  
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sugar_in_your_tea@sh.itjust.works ⁨4⁩ ⁨weeks⁩ ago

Nobody ever called the purely 8 bit Motorola M6800

Sure, but that was a long time ago. Lithography marketing also used to make sense when it was actually based on real measurements, but times change.

All those chips you’re talking about were from >40 years ago. Times change.

Today it’s way way more complex, and we may call it x86-64, but that’s the instruction set, the modern x86-64 CPU is not 64 bit anymore.

Sure, yet when someone describes a CPU, we talk about the instruction set, so we talk about 32-bit vs 64-bit instructions. That’s how the terminology works.

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- Buffalox@lemmy.world ⁨4⁩ ⁨weeks⁩ ago
  I have no idea what has gone wrong here? I’m not denying that a modern Intel or AMD or Arm CPU generally is called a 64 bit CPU.
  I’m just stating that if they had to be measured by their actual capabilities, a modern Ryzen CPU for instance, is actually closer to being a 256 bit CPU.
  
  But there can be absolutely no doubt that Address bus was NEVER used to determine the bit width of a CPU, that would simply be ridiculous, as it ONLY determines addressable RAM and nothing else.
  
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  - sugar_in_your_tea@sh.itjust.works ⁨4⁩ ⁨weeks⁩ ago
    
    I’m not denying that a modern Intel or AMD or Arm CPU generally is called a 64 bit CPU
    
    That seems to be exactly what you’re arguing about, unless I have misread this entire thread.
    
    If we want to highlight other capabilities, we should use different terminology than “X-bit” because that has been pretty much universally agreed upon to refer to instruction sizes and addresses, not data pipelines. And we do that, product spec sheets refer to extensions to point out the unique capabilities they offer (e.g. Intel was pretty famous for supporting AVX-512 almost 10 years before AMD).
    
    That said, now that 32-bit is essentially dead, the “X-bit” marker is essentially dead, and saying something is 256-bit or whatever today is just going to confuse people. People have gotten into the habit if talking about specific capabilities if it’s relevant (which it isn’t for most people, who just care about “IPC”).
    
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    Buffalox@lemmy.world ⁨4⁩ ⁨weeks⁩ ago
    
    the “X-bit” marker is essentially dead,
    
    That was kind of the point, it’s ridiculous to think a modern CPU hasn’t evolved dramatically since the introduction of mainstream 64 bit in 2003.
    It’s still called 64 bit, but there are so many developments.
    
    for most people, who just care about “IPC”
    
    Exactly, and that is achieved by a modern core operating at about 256 bit internally, to achieve faster execution.
    
    I’m not arguing it’s wrong to call it 64 bit, because there is no “true” bit width to call it. So we might as well still call it 64 bit, because it describes the core instruction set. (not just pointers as was claimed by someone else) My point was just that it doesn’t really describe the dramatic development of the CPU as a whole, and even the individual cores are more complex in hardware, despite the main instruction set remains the same.
    
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