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16-bit & 32 bit

By jason9177 ·
what do 16-bit & 32 bit programs/windows means???

is there anywhere i can read up for informations?

thanks

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by Chris910 In reply to 16-bit & 32 bit

These terms refer to the way that they are programed and compiled. In essence this is just a way of optomising the program for the computers processor. A 16 bit application is setup for a 16 bit data regester on the processor and the 32 bit is setup for a 32 bit data regester.
(Note: depending on the program, some 16 bit applications will run faster than the same program compiled for a 32 bit data path)

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by p.j.hutchison In reply to 16-bit & 32 bit

It determines how much memory a program can access.
OS such as DOS and Windows 3.1 is 16 bit as they were designed on old Intel 80386 or later processors.
DOS can only access upto 640K RAM. OS 3 with enhanced memory management can access more.

OS such as Windows 95,98,NT,2000,XP are 32 bit OSs which can access upto 4GB of RAM on Pentium based systems.
Windows XP 64 bit edition can access Terabytes of memory on Itanium and eventually Athlon 64 processors.

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by lrund In reply to 16-bit & 32 bit

There are two definitions for 16 bit and 32 bit. The first deals with programmming in regards to the registers. A 16 bit program has a limitation of 65535 bytes of accessable memory while a 32 bit program can access upto 4 GB of memory. But wait, didn't DOS run upto 640K in 16 bit mode, how could this be if there is a limitation of 65535 bytes. Now we come to the hardware definition.
The reason that you could access 640K using a 16 bit processor was because of the supported memory bank switching within the hardware level and access to the DMA from the CPU for accessing the expanded memory. Also many of the early machines had 32 bit processors starting with the 80386, but they were limited to 2 GB of memory, why? It was a hardware limitation of the motherboard and chipset. The real difinition at the hardware level is 16 and 32 bits refers to the width of the bus between the cpu and memory.

The bottom line is that the number of bits does not limit the amount of memory that can be accessed, it is the hardware that limits the amount of memory. With creative programming and hardware level controls, even a 16 bit program can access any amount of memory.

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by wlbowers In reply to 16-bit & 32 bit

Computer processors evolved through the years.

8bit, 16bit, 32bit. This described in computer terms the amount of data, and memory that could be addressed or processed at one time.

A 32bit computer can process twice the amount of data than a 16bit program.

This is all dependent on the program and os being written to take advantage of the 32bit structure.

Read up here:

http://en.wikipedia.org/wiki/16_bit

Lee

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