Computer - difference between 32 bits and 64 bits

Wikitechy | 632 Views | windows | 26 Jun 2016

 

Computer - difference between 32 bits and 64 bits

General Purpose registers :

  • The GPR holds data that is processed by CPU and hence represent the data types of the CPU.
  • CPU access the data from register for scheming a memory address.
  • CPU's directly-mapped memory space is 

4GB for a 32-bit CPU and 

16EB (Exabyte) for a 64-bit CPU.

  • GPRs are 

32-bits in size on 32-bit machines, 

64-bits in size on 64-bit machines.

Registers wise :

  • 32-bit CPU holds 8 Registers only. 
  • 64-bit CPU holds 16 Registers.
  • Register is similar to caching layer between the processor and the memory. 
  • Register data access is quicker when compared with the main memory. 
  • More registers means better data storage and access, with lesser memory requirements. 

Virtual memory wise :

  • A 32-bit processor has access to 2 ^ 32 or approx 4GB of virtual memory. 
  • In a 64-bit processor, this increases to 2 ^ 64 or 16 Exabytes. 
  • When memory availability is excess, capacity to store data increases with lesser hits to the hard disk. 
  • Reading and writing to memoryis faster and hence improves performance.
  • A 32-bit memory addresscan refer upto 4 GB of memory. 
  • The x86-64 bit permits for 48-bit memory addresses with to 256 TB addressable space.

Applies to :

  • Windows 1
  • Windows 8.1
  • Windows 8
  • Windows 7
  • Windows Vista

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