This document discusses how to determine if a CPU is 32-bit or 64-bit. It provides four methods: checking system properties in Windows, using CPU-Z software, using Belarc software, or checking the processor specifications online. While registry and MSINFO32 can also indicate the bitness, they only work if running a 64-bit OS. 64-bit CPUs can run both 32-bit and 64-bit OSes, while 32-bit CPUs can only run 32-bit OSes. It is not possible to upgrade between 32-bit and 64-bit OSes.

1. How to determine if CPU is 32 bit Or 64 bit ?
Ashwin Pawar
ashwinwriter@gmail.com
Oct, 2010

2. This is of the most common question asked on the net, when it comes to determining
whether you have a 32 bit or 64 bit processor. Chances are you have a 64bit processor pc
but you may be under the impression that you have a 32 bit processor for the fact that you
are running a 32 bit Operating System.
To start with, a 64 bit processor can talk to both 32 bit or 64 bit operating system, where
as a 32bit processor can only talk to 32 bit operating system.
Let’s find that out!
There are 4 simple ways you can determine if you have a 64bit processor :
1. (On Vista) Open Performance Information and Tools by clicking the Start button ,
clicking Control Panel, clicking System and Maintenance, and then clicking
Performance Information and Tools. Click View and print details.
Note : If your computer is already running a 64-bit version of Windows, you won't
see the 64-bit capable listing.
2. You can check if your processor supports 64-bit by using CPU-Z, a free little
program that displays system info. (If it says AMD64, x86-x64 or EM64T next to
Instructions, then it is a 64bit processor).
http://www.cpuid.com/cpuz.php
3. You can also download free software from blarc, it builds a detailed profile of
your installed software and hardware. (If it says 64bit ready, it is a 64bit
processor).
http://www.belarc.com/free_download.html
4. Go to Intel website, and look for the value next to "Instruction Set" under the cpu
specification. (If it says 64, that means you have a 64bit processor).

3. Point of confusion :
You may come across following methods on the net to find the processor type
information using regedit & msinfo32, which can be little deceiving or rather misleading
if used in wrong context.
First Method:
Using regedit:
HKEY_LOCAL_MACHINEHARDWAREDESCRIPTIONSystemCentralProcessor0
look for ‘Identifier’ or “Platform ID’.
Second Method:
Using MSINFO32: Go to Start -> Type msinfo32.exe
From the System Information page under System Type.
These two methods will return correct information provided you are alerady running a
64bit Operating System, but If you are running a 32bit Operating system then the chances
are you will see the cpu type as : x86 , which is incorrect.
In other words, If you are running a 32-bit Windows on a 64-bit-capable CPU, you will
still get x86 as cpu type. Hence, It is always advisable to check your prcessor type using
the tools/methods shown at the beginning of this article.
But, both these methods are perfectly correct to find out if a computer is running 32 or 64
bit of windows operating system.
The next logical question would be :
Why do vendors sell 64-bit processors with 32-bit operating systems?
When purchasing a new computer, you may find that the default operating system is a 32-
bit edition even though the processor supports 64-bit. This is especially true for desktop
systems. The reason for this is that many desktop applications don't benefit significantly
from the extended memory support on 64-bit systems, and there is some risk of some
compatibility issues with 32-bit desktop applications.

4. Let’s Get this Right : 64 bit Processor History ?
64-bit processors have been around for a very long time. Intel and HP began development
of the 64-bit Itanium processor in 1994 under the codename Merced.
Itanium was finally introduced in May 2001 but It was strictly considered a
server/workstation processor and not a processor for use in desktop PCs.
Additionally, the IA-64 (Intel Architecture 64-bit) instruction set used by the Itanium was
completely different from the IA-32 (Intel Architecture 32-bit) instruction set used by
standard Intel and AMD PC processors.
The start of real 64-bit computing for standard PCs began on April 22, 2003 when the
AMD Opteron processor was introduced. The Opteron did not use the IA-64 instruction
set from the Itanium, but instead included 64-bit extensions that worked on top of the
existing IA-32 instructions developed by Intel. This would allow for greater compatibility
with existing software, and make it easier for 32-bit and 64-bit computing to coexist on
the same platform.
Unfortunately like Itanium, Opteron was also a server/workstation processor, considered
far too costly for standard desktop or mobile PCs.
Finally on September 23, 2003, AMD released the Athlon 64, truly the first desktop PC
processor supporting 64-bit extensions. This would be the breakthrough needed for any
significant 64-bit software development to occur. The most signification development
was that AMD released these extensions before Intel.
On February 17, 2004 Intel introduced its first Pentium 4 processors with 64-bit
extensions, the very same extensions as introduced by AMD. Hence, this would allow the
same software to work on both AMD and Intel processors, a win win situation for all.
Interesting to know that:
• AMD calls these extensions AMD64 technology.
• Intel calls them EM64T (Extended Memory 64 Technology).
• Microsoft calls them x64.
Conclusion : It is a 64-bit Processor based on 32-bit Intel-compatible (x86) processor
architecture.

5. Facts:
1. A 64-bit version of Windows Vista supports from 1 GB of RAM to more than 128
GB of RAM, but 4 GB minimum is recommended.
2. A 32-bit version of Windows Vista can access up to 4 GB of RAM only, above
this limit, the physical memory is not addressable by 32-bit versions of Windows
Vista.
3. All hardware devices need 64-bit drivers to work on a 64-bit version
of Windows.
What do you mean by 32 bit :
The bit size of a processor refers to the size of the address space it can reference, and 32
bit is nothing but 2^32 bytes , which is an equivalent of 4,294,967,296 bytes which
means that the CPU can access up to "4,294,967,296" which is ‘4th GB of data’
maximum.
Can you upgrade from 32 Bit to 64 Bit OS ?
Ans: NO! There is no way to upgrade from 32 Bit to 64 Bit, they are 2 totally different
architectures built on different code. Further, there is also no way to downgrade from 64
bit to 32 bit either. Solution : Full fresh install.
Caution :
• If you do decide to go for 64 bit OS. Most important, check for Device Driver
support first, and then check your most used applications if they have a support
for 64bit OS, and after that check the rest of the software, make sure they have a
64 Bit OS support as well.
• All your programs will have to be reinstalled. Make a thorough backup of your
important files before doing the installation.
References:
http://windows.microsoft.com/en-US/windows-vista/32-bit-and-64-bit-Windows-
frequently-asked-questions
http://www.lumerical.com/64-bit_photonic_design.php
http://www.microsoft.com/windows/pc-scout/laptop-speed-facts.aspx
http://support.microsoft.com/kb/946765
http://support.microsoft.com/kb/827218
http://support.microsoft.com/kb/556009