Saturday, 19 July 2014

32-bit and 64-bit computer system

Hello everyone,
This post is about the 32-bit and 64-bit computer system. 

32-bit Operating System
32 bit operating system operates/utilizes data in 32 bit pieces. It can address (point to or index to) 2^32 i.e. 4 Gigabytes of memory in one go.
Ex. Windows 95, 98, XP(32 bit addition) are 32 bit operating system. 

64-bit Operating system:
64 bit operating system utilizes data in 64 bit pieces. It can address or can point 2^64 i.e.16 Exabyte of memory in one go, which is equals to 17.2 BILLION Gigabytes.
Ex. Windows 8, Windows 7, Windows Vista comes in 64 bit operating system. 

It means as the number of bits increases, there are important benefits:
  1. If there is more bit in operating system, it means that data can be processed in larger chunks. It also means that more accurately data can be processed.
  2.  Second benefit is our system can point to or address a larger number of locations in memory. 
  3. As the bit increases the more data can be processed at once, hence faster the system can operate.
Now, How to apply the conversions:

For these following Data Measurement Chart is used:

Data Measurement Unit Size
Bit Single binary digit (1 or 0)
Byte 8 bits
Kilobyte (KB) 1024 bytes (210 bytes)
Megabyte (MB) 1024 kilobytes (220 bytes)
Gigabyte (GB) 1024 megabytes (230 bytes)
Terabyte (TB) 1024 gigabytes (240 bytes)
Pentabyte (PB 1024 terabytes (250 bytes)
Exabytes (EB) 1024 pentabytes (260 bytes)

In 32 bit operating systems:

Since 32 bit operating system can point up to 232 memory addresses. It means memory size can be of 232 bytes i.e.

210 * 210 * 210 * 22 = 4 * 230
   = 4 GB
It means 32 bit operating system is compatible up to 4 GB memory size.

In 64 bit operating systems:

Similarly, 64 bit operating system can point up to 264 memory addresses. It means memory size can be of 264 bytes i.e.
210  * 210 * 210 * 210 * 210 * 210 * 24 = 16 * 260
    =  16 EB

Hence, 64 bit operating system is compatible up to 16 EB memory size. But due to some licence issue it can compatible with less size of memory than 16 EB memory size.

Supportability Concept:

In this concept, the main issue is that computer works from hardware such as the processor, through the operating system, to the highest level which is application. So the computer hardware is designed first, the matching operating systems are developed and finally applications appears. Here the Backward Compatibility concept is applied. According to which back levels must be compatible with the higher levels.
The following table explains the backward compatibility concept more clearly:

Processor Operating System Application Compatibility
64 bit 64 bit 64 bit Yes
64 bit 64 bit 32 bit Yes
64 bit 32 bit 32 bit Yes
64 bit 32 bit 64 bit No

It means a 32 bit operating system will run on 32 bit or 64 bit processor without any problem. A 32 bit application will run on a 32 bit or 64 bit operating system without any problem. But a 64-bit application will only run on a 64-bit OS and a 64-bit OS will only run on a 64-bit processor. The main reason that 32-bit will always run on 64-bit is that the 64-bit components have been designed to work that way. So the newer 64-bit systems are backward-compatible with the 32-bit systems. One important point that it is not possible to install a 32-bit device driver on a 64-bit operating system. This is because device drivers run in parallel to the operating system. The emulation is done at the operating system level so it is available to the higher layer, the application, but it is not available to the device driver which runs on the same level.Hardware virtualization is the exception to the rule.