32-bit and 64-bit Operating Systems

Operating systems nowadays come in 2 types. 32-bit is the standard and widely known type, and 64-bit, which is comparatively lesser known. 32 and 64 bit architectures mainly refer to the types of data units. A 64-bit architecture supports 64 bits wide data units, which allow for wider processing capabilities, compared to 32-bit architecture.

The major differences between these 2 operating system types are memory accessibility/management and security. A 64-bit operating system can theoretically access in excess of 128 GB of RAM, while a 32-bit operating system is limited to about 4 GB of RAM, due to the virtual address space being limited simply by the size of a 32-bit value. And so, the maximum memory accessible is 4096 MB, or 4 GB, as given:

2(power 32) = 4,294,967,296

4,294,967,296 / (1,024 x 1,024) = 4,096

Assuming in a 32-bit environment 4 GB of memory is available; the space is evenly divided into 2 parts. 2 GB is dedicated for kernel usage and 2 GB for application usage. Even though the application gets its own 2 GB, all applications still share the same 2 GB reserved for kernel usage. Herein lies a limitation.

Even with the fairly limited amount of memory available, a 32-bit operating system still shares the memory with attached I/O devices, which include graphic cards and other memory-mapped devices. Thus, we are left with even lesser memory. In other words, if you run applications that use more than 2 GB of memory, a 64-bit operating system is strongly recommended. Also, applications designed to take advantage of 64-bit architectures show improved performance.

In a 64-bit operating system, the physical memory limit is 192 GB and virtual address space is 8 terabytes. This means that we won’t have a shortage of physical or virtual address space anytime soon.

Intel Pentium 4 (Northwood)

AMD Athlon XP (Barton)

A 64-bit operating system can only run on a processor that supports 64-bit processing. Most modern processors support this feature and should be able to run a 64-bit operating system. Intel Pentium 4 processors from the Northwood generation, and AMD Athlon XP processors were some of the last processors to use only 32-bit (x86) architectures. 64-bit operating systems have higher requirements than 32-bit operating systems, and one has to consider a few more factors:

1. Device drivers must be digitally signed to be installed on a 64-bit OS.
2. 64-bit device drivers may not be available for older hardware; and 32-bit device drivers are not supported at all.
3. Some 32-bit programs may not be entirely compatible with a 64-bit OS.
4. Not all hardware may be compatible with a 64-bit OS.
5. 64-bit operating systems do not support 16-bit programs, while 32-bit operating systems partly support them.

In conclusion, 64-bit operating systems are the future for complex applications and improved performance, but for the common man, who has limited needs and no requirement for high end processing capabilities, 32-bit operating systems will do just fine for a few more years.

  1. Yesh December 29, 2010
  2. Satish December 29, 2010
  3. Satish December 29, 2010
  4. Phoenix December 29, 2010
  5. Phoenix December 29, 2010
  6. chaitanya December 30, 2010
  7. Phoenix December 30, 2010
  8. jibran January 16, 2011
  9. vikash July 13, 2012

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