Budget 0-20k 32 bit or 64 bit

harshit verma

harshit verma

Disciple
ALPHA17.

Kindly explain is it necessary to have 64 bit version windows in your desktop if you want to increase the ram or memory power beyond 4gb. i have come to know if you put ram more than 4 gb in 32 bit version it will not address. is it true.

please solve this mystery.
 
yes. 32bit means 2^32 = 4GB.

on 32bit windows windows has 4GB of address space out of which 2GB is reserved for kernel and the remaining 2GB is available for user space programs. with some boot switches you can change this to 1GB for kernel and 3GB for userspace programs.

There are some settings like PAE (physical address extention) with which you can extend the address space to more than 4GB on 32bit operating system. but people simply switched to 64bit os.

btw, you need to have 64bit processor to work with 64bit os. all modern processors are 64bit anyways. :) hope that helps.
 
Thanks for prompt reply. It means i should adopt presently only 64bit. btw, how much memory is reserved for kernel in 64bit version windows.
pl. clear
 
to clarify, memory is not reserved... address space is reserved. i.e., address of first 2GB is reserved to kernel.

there are few operating system concepts like memory addressing, paging etc... you need to understand to get clear picture.

so in a nut shell, even in 64bit os half of the address space is reserved for kernel, but 2^64 is something close to 16 exabytes. so you have a lot of address space available. exabyte is kb->mb->gb->tb->petabyte->exabyte.

basically you have something known as address bus, a data bus and general purpose registers on computers. operating systems are written accordingly. if you want to read a byte from memory into a register you will need an address. so basically in 32bit system, you will specify the 32bit address and a 32bit register to fetch the value, anything less than 32bit or anything more need shift operations on the registers which take up cpu cycles. So when you are specifying an address on 32bit processor you cannot specify more than 4GB adress so with PAE you will need some extra operations to get to greater than 4G address.

from history if you ever known DOS3.2, the max system ram was about 640kb due to the 16bit limitation.
 
Back
Top