Originally posted by: Accord99
Originally posted by: Vee
A 32-bit programs cannot easily use more than 2GB space of addresses for code and data. And this has nothing to do with physical memory size. It's the process virtual space. And it gets fragmented!
This is the really big need for 64-bit computing. We're at limit with 32-bit. That limit is 2GB and you can compare it to the old 640KB limit of early PCs.
Most typical programs don't come close to the 2GB limit. And the mainstream S745 platform generally can't even handle 3GB of memory, less than Intel's dual channel motherboards.
First of all, this is not the question of "most typical" programs today. It's the question of what we want to use the computer for.
Secondly it's about the space available to the process! Not size of RAM!
I'm already using up the 2GB space, when I'm working. That's an engineering app. But here's a few other cases that can use a larger than 2GB process space, approximately from like today: Editors and toolsets for 3D games, 3D games, 3D modelling tools and computergenerated 3D imagery and animation, cinematic editing.
Thirdly, what's the main reason for development of DDR2 and DDR3? Speed? No, signal quality enabling more RAM.
Well, that sounds a bit strange. But it's all up to judgement. Anyway, there's no technical similarities between the 16 to 32 bit migration and the 32 to 64 bit migration. Two completely different things.
Yes no comparison at all. 16->32 bit was an essential migration with massive benefits to all users and still took years for a complete transition. 32->64 is more niche at the moment, and not absolutely necessary for years to come.
16->32 bit was primarily migration from segmented addressing to linear addressing. As such it was real nice. Since the opportunity was taken to also change the OS&program model to multithreaded and with real virtual memory and memory protection, it was even nicer. ...And almost necessary. At least it was a big relief.
32->64 bit on the other hand is certainly really a necessity, since it is about expanding process space and removing a 2GB limit that we are banging our heads against. A situation that is only going to become worse, and has not much to do with the amount of available physical RAM, which everybody seem to wrongly assume. And again, the opportunity is taken to change the ISA to more flexible use of registers. Which should grant a nice performance kick. But that's just icing on the cake, not the reason for 64-bit computing. Everything else is just Intel trying to mislead the market.