# What is the max. capacity of RAM in 32-bit machine? Why it is not 16GB? [closed]

This question is inspired from a question in stackoverflow here

To what I know,

for 32bit machines, we can have 2^32 combination set of instructions.

so for a max capacity of a RAM in 32-bit machine, it should be able to accommodate 2^32 instructions set, which is

2^32 = 4294967296 instructions set

so as 32 bits = 4 bytes, the RAM capacity should be 4294967296 * 4 bytes = 17179869186 bytes

which is same as -->

17179869186/1024 = 16777216 kB

16777216/1024 = 16384 MB

16384/1024 = 16GB

so I guess the max capacity of RAM that a 32-bit machine can hold is 16GB.

But sounds like 4GB is the correct answer. What's wrong with me???

-

## closed as not a real question by Ƭᴇcʜιᴇ007, afrazier, Nifle, studiohack♦Aug 2 '11 at 11:32

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

You're confusing "instruction sets" with "memory addressing" to say the least. :) –  Ƭᴇcʜιᴇ007 Aug 1 '11 at 16:16
appreciate if you can help correct me –  Kit Ho Aug 1 '11 at 16:17
@Kit, you basic confusion is that the size of a pointer is not the same as the size of the thing pointed to. A pointer on a 32-bit machine is 4 bytes wide, but a single memory address (the thing that the pointer points to) is only one byte wide. –  JSBձոգչ Aug 1 '11 at 17:47
The confusion here is between the size of the processor word (32 bits in this case) and the size of the addressable memory unit (in the case of current general purpose machines that is 1 byte = 8 bits). So yes, the processor can load four addressable memory units at a time. –  dmckee Aug 1 '11 at 18:48
I also don't understand the close votes here - this seems like a real question to me (but then, that's why I answered it). –  Shinrai Aug 2 '11 at 14:41