no CPU has ever been called by the width of the address bus EVER.
Yes they have, and that’s what the vast majority of people mean when they say a CPU is 32-bit or 64-bit. It was especially important in the transition from 32-bit to 64-bit because of all the SW changes that needed to be made to support 64-bit addresses. It was a huge thing in the early 2000s, and that is where the nomenclature comes from.
Before that big switch, it was a bit more marketing than anything else and frequently referred to the size of the data the CPU operated on. But during and after that switch, it shifted to address sizes, and instructions (not including the data) are also 64-bit. The main difference w/ AVX vs a “normal” instruction is the size of the registers used, which can be up to 512-bit, vs a “normal” 64-bit register. But the instruction remains 64-bit, at least as far as the rest of the system is concerned.
Hence why CPUs are 64-bit, all of the interface between the CPU and the rest of the system is with 64-bit instructions and 64-bit addresses. Whether the CPU does something fancy under the hood w/ more than 64-bits (i.e. registers and parallel processing) is entirely irrelevant, the interface is 64-bit, therefore it’s 64-bit.
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.
I guess you know more about hardware nomenclature Linux kernel developers, because they call modern Intel/AMD and ARM CPUs amd64 and aarch64, respectively.
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.
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.
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.
sugar_in_your_tea@sh.itjust.works 3 days ago
Yes they have, and that’s what the vast majority of people mean when they say a CPU is 32-bit or 64-bit. It was especially important in the transition from 32-bit to 64-bit because of all the SW changes that needed to be made to support 64-bit addresses. It was a huge thing in the early 2000s, and that is where the nomenclature comes from.
Before that big switch, it was a bit more marketing than anything else and frequently referred to the size of the data the CPU operated on. But during and after that switch, it shifted to address sizes, and instructions (not including the data) are also 64-bit. The main difference w/ AVX vs a “normal” instruction is the size of the registers used, which can be up to 512-bit, vs a “normal” 64-bit register. But the instruction remains 64-bit, at least as far as the rest of the system is concerned.
Hence why CPUs are 64-bit, all of the interface between the CPU and the rest of the system is with 64-bit instructions and 64-bit addresses. Whether the CPU does something fancy under the hood w/ more than 64-bits (i.e. registers and parallel processing) is entirely irrelevant, the interface is 64-bit, therefore it’s 64-bit.
Buffalox@lemmy.world 3 days ago
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.
tekato@lemmy.world 3 days 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.
Buffalox@lemmy.world 3 days 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.
sugar_in_your_tea@sh.itjust.works 3 days ago
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.
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.
Buffalox@lemmy.world 3 days 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.