Way back when, processors were 16-bit. That means that they could only reference 64 kilobytes at a time (that's 2^16 or 65536 bytes or 64 kilobytes). If someone needed more memory they would have to use what is called the "segmented model". What that means is they would have to point the processor at another 64 kilobytes of memory. This was not only inefficient, but also dangerous.
All this is why Intel then introduced their 80286 processer. This processor was 32-bit, which means it can address 4 gagbytes of memory (that's 2^32 or 4294967296 bytes or 4 gigabytes). What this processor also introduced (in a somewhat crude fashion) is what is called "protected mode". This forbids programmers from messing with segments, which therefore improved security between programs running simultaneously (multitasking). This wasn't a problem though, as nobody ever thought we would need more than 4 gigabytes of RAM.
Today, it's a different story. 4 gigabytes of RAM is becoming more and more common. That's what the 64-bit processor is going to solve. 64-bit processors allow 16 petabytes or memory to be addressed at one time (that's 2^64 or 18446744073709551616 bytes or 16 petabytes or 16777216 gigabytes or 16 petabytes)! With the talk of processor speeds no longer increasing exponentially and such, I seriously doubt we'll need more than that anytime soon.
Oh, and by the way, AMD is cheap, they're going to (for the sake of making more money) release their Opteron processer as a 48-bit processor. It can do 64-bit math, it has 64 bit registers, but it's only 48-bit. This means we're only going to be able to address 0.000244140625 petabytes:( (that's 2^64 or 281474976710656 bytes or 256 gigabytes or 0.000244140625 petabytes). But, who cares, right? We can just worry about it ~10 years down the road.
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Yea.
Way back when, processors were 16-bit. That means that they could only reference 64 kilobytes at a time (that's 2^16 or 65536 bytes or 64 kilobytes). If someone needed more memory they would have to use what is called the "segmented model". What that means is they would have to point the processor at another 64 kilobytes of memory. This was not only inefficient, but also dangerous.
:( (that's 2^64 or 281474976710656 bytes or 256 gigabytes or 0.000244140625 petabytes). But, who cares, right? We can just worry about it ~10 years down the road.
:)
All this is why Intel then introduced their 80286 processer. This processor was 32-bit, which means it can address 4 gagbytes of memory (that's 2^32 or 4294967296 bytes or 4 gigabytes). What this processor also introduced (in a somewhat crude fashion) is what is called "protected mode". This forbids programmers from messing with segments, which therefore improved security between programs running simultaneously (multitasking). This wasn't a problem though, as nobody ever thought we would need more than 4 gigabytes of RAM.
Today, it's a different story. 4 gigabytes of RAM is becoming more and more common. That's what the 64-bit processor is going to solve. 64-bit processors allow 16 petabytes or memory to be addressed at one time (that's 2^64 or 18446744073709551616 bytes or 16 petabytes or 16777216 gigabytes or 16 petabytes)! With the talk of processor speeds no longer increasing exponentially and such, I seriously doubt we'll need more than that anytime soon.
Oh, and by the way, AMD is cheap, they're going to (for the sake of making more money) release their Opteron processer as a 48-bit processor. It can do 64-bit math, it has 64 bit registers, but it's only 48-bit. This means we're only going to be able to address 0.000244140625 petabytes
-iamthecoolest, xeon at #osdev (irc.freenode.net), http://www.xeon.terminal-n.com/
P.S. I'm new!