What determines the limit of RAM that can be connected to a processor

[Embedded_Geek]

Can anyone please help me know How to determine the maximum limit of RAM that can be connected to a processor like Intel dual core etc.

Intel Pentium IV is of 32 bit and I have a dual core of 32 bit as well. But the amount of RAM supported by each of these processor are different even though both of them are 32 bit processor.

 

[IanP]

Registers in x86 PCs are limited to 32 bits, which means the biggest number that can be stored in that register is 2^32, or 4,294,967,296; which means that the CPU can access up to "ADDRESS 4,294,967,296" which is the 4th GB of data.

The problem is that the CPU also access I/O devices (printer, USB, keyboard, mouse, monitor, etc.) by assigning them an address as well. So it reserves half a GB or so of the memory addresses to talk to the I/O devices... So you have 4GB - ~0.5GB -> 3.5 GB (on Windows it is 3.2GB).

Difference Between 32 Bit (x86) and 64 Bit (x64)

:wink:
IanP

 

[ckshivaram]

CPU doesn't "handle" Ram. This is a motherboard/operating system that "handles" it.

Your Motherboard RUNS the ram. Your Operating system has to Address the RAM to be used by the computer.
Most computers can handle up to like 16 gb of RAM (or maybe even more depending on the type of RAM). But your Operating system my limit that. With a 32-bit OS you can only address up to 4gb of memory. Because windows itself needs some address you only get something like 3.2 gb. So you could even have 10gb in your computer, but your Operating system would only "see" 3.2 gb. But with 64-bit OS you can get up to like 128 gb or something?

---------- Post added at 14:49 ---------- Previous post was at 14:46 ----------

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