By the way, the AMD athlon 64-bit launched 2003. The PS3 launched in 2006. I had an AMD64 bit process in my laptop in 2005.
What wasn't viable?
By the way, the AMD athlon 64-bit launched 2003. The PS3 launched in 2006. I had an AMD64 bit process in my laptop in 2005.
What wasn't viable?
They would have started designing the systems in 2003, and one of the first choices is CPU partner.
Do you trust the new line of CPUs that just launched that year?
Because consoles don't use off-the-shelf CPUs for many reasons. Neither Intel nor AMD of that time would even consider making a bespoke CPU for Sony or MS.
Even they could use off-the-shelf SKU it wouldn't be viable - neither one had one that fits in power envelope (not that it helped xbox...)
I have some confidence that AMD's acquisition of ATI had a huge impact.
That allowed both a CPU and an advanced GPU to be on the same die.
They also wisely sold Global Foundries, and were able to scale with TSMC.
Yeah that part didn't make sense, not to mention that neither the PS3 nor the 360 were running 64-bit software. They didn't have enough memory for it to be worth it.
you don't need memory to make 64 bit software worth it. Just 64 bit mathematics requirements. Which basically no video game console uses as from what I understand 32-bit floating point continue to be state of the art in video game simulations
Fundamentally it's still a memory limitation, just in terms of memory latency/cache misses instead of capacity. If you double the size of your numbers you're doubling the space it takes up and all the problems that come with it.
No it isn't. The 64-bit capabilities of modern CPUs have almost nothing to do with memory. The address space is rarely 64 bits of physical address space anyways. A "64-bit" computer doesn't actually have the ability to deal with 64 bits of memory.
If you double the size of numbers, sure it takes up twice the space. If the total size is still less that one page it isn't likely to make a big difference anyways. What really makes a difference is trying to do 64-bit mathematics with 32-bit hardware. This implies some degree of emulation with a series of instructions, whereas a 64-bit CPU could execute that in 1 instruction. That 1 instruction very likely executes in less cycles than a series of other instructions. Otherwise no one would have bothered with it
Typically, it doesn't have the ability to deal with a full 64 bits of memory, but it does have the ability to deal with more than 32 bits of memory, and all pointers are 64 bits long for alignment reasons.
It's possible but rare for systems to have 64-bit GPRs but a 32-bit address space. Examples I can think of include the Nintendo 64 (MIPS; apparently commercial games rarely actually used the 64-bit instructions, so the console's name was pretty much a misnomer), some Apple Watch models (standard 64-bit ARM but with a compiler ABI that made pointers 32 bits to save memory), and the ill-fated x32 ABI on Linux (same thing but on x86-64).
That said, even "32-bit" CPUs usually have some kind of support for 64-bit floats (except for tiny embedded CPUs).
"Bitness" of a CPU almost always refers to memory addressing.
Now you could build a weird CPU that has "more memory" than it has addressable width (the 8086 is kind of like this with segmentation and 8/16 bit) but if your CPU is 64 bit you're likely not to use anything less than 64 bit math in general (though you can get some tricks with multiple adds of 32 bit numbers packed).
But a 32 bit CPU can do all sorts of things with larger numbers, it's just that moving them around may be more time-consuming. After all, that's basically what MMX and friends are.
The original 8087 implemented 80-bit operands in its stack.
It would also process binary-coded decimal integers, as well as floating point.
"The two came up with a revolutionary design with 64 bits of mantissa and 16 bits of exponent for the longest-format real number, with a stack architecture CPU and eight 80-bit stack registers, with a computationally rich instruction set."
https://en.wikipedia.org/wiki/Intel_8087
Parts of the 360 did. The hypervisor ran in 64bit mode, and use multiple simultaneous mirrors of physical address space with different security properties as part of its security model.
You have to remember that the AMD and Intel of today are very different companies than they were 20-25 years ago. AMD split off it's fab capabilities, acquired ATI, adopted TSMC as a fab, and developed a custom silicon business.
At that time AMD wasn't in the custom CPU business, AMD64 was a new unproven ISA, and x86 based CPUs of that time were notoriously hot for a console. These were also some of the reasons why Microsoft moved away from the Pentium III it had used in the original Xbox.
The PS3 was launched in 2006 but the hardware design was decided years earlier to provide a reference platform for the software.