What is system capacity?

Question

Operating Systems

What's up, software.
I kind of already tried to figure it out several times, and I thought that, in fact, I did it, but I still didn’t fully understand, since I’m writing here.
32 bit vs 64 bit - what is it?
That is, when I download something, an application, a new OS, and so on, there is always a choice: 32 or 64 bits. Obviously, 64 is faster. But what is it? Processor architecture?
32 bit applications are launched by me, as far as I remember, my percent is i7 4670. It is probably 64 bit.
In general, please give an explanation so that I don’t get confused anymore.
PS : Sometimes I see how people write that - "oh, won't it be on x86?" i.e. they won't run 64 bits?

Answer 1

32 and 64 - bit depth of the machine word, to generalize.
Most of the time it has nothing to do with speed.
A has to do with operations with large numbers (64-bit).
In particular, such numbers can be addresses of variables in memory. Accordingly, 32-bit applications (and the OS is also an application) cannot access more than 4 GB of memory - a larger address simply will not fit into 32 bits.
Accordingly, the bit depth of the system will determine what bit length of the machine word it supports. Now it seems that they always maintain compatibility for 32 bits.
Accordingly, the bit depth of the processor is essentially the same - what size of a machine word it supports.
Now on 64-bit architectures there is always compatibility with 32-bit ones. But this is optional. But back - no. Those. if you have a 32-bit system / processor, then 64-bit applications will not start.