Whenever you install an App or a game you have probably seen the option of 32-bit and 64-bit versions, even your PC might have sticker on it saying that whether it consists of a 32-bit processor or a 64-bit processor, but does it really even matter?
What is a bit in a processor?
A bit is used to represent the amount of memory it can store. In computers, all the data is stored in binary format, i.e. either 0 or 1. One bit can store either a ‘0’ or ‘1’. A bit is too small to be much use. It is the building block of storage.The more bit you use the more data it can store.
Group 8 bits together to make 1 byte. e.g. 1 1 0 1 0 0 1 0
One byte can store one character, e.g. ‘A’ or ‘x’ or ‘$’. In short, we can say that the more number of bits we add the more values we can represent in binary.
A processor is the logic circuitry that responds to and processes the basic instructions that drive a computer. The four primary functions of a processor are fetch, decode, execute and writeback.
Until 1990’s the processor used were mostly 32-bit processor, but they were slower and could not execute and run larger software smoothly. So the 64-bit processors were then used by the public by early 2000. The 64-bit processors were available before that, but it wasn’t used by the public because of lack of compatible programs.
AMD was first to decide that the market needed a 64-bit CPU that was compatible, with the x86 (32-bit) family. As a marketing appeal, they called it the “x86-64” family, and they were hugely successful. So much so that Intel ended up following with their own 64 bits CPU based on x86. Later on, the name was shortened from “x86-64” to “x64” just because it was shorter and easier.
But what does 32 bit and 64 bit really mean?
It represents the size of the registers. Registers are small storage mostly inside the CPU itself, very costly, but very fast as they are closest to the CPU. A 64-bit register can thus store and process more data than 32-bit, which can store more than 16bit and so on.
The use of registers is more beneficial because it is the fastest among other memory components. It loads the next instruction required from the RAM onto itself to make it available to the CPU at the fastest time possible. In simple words processing is done much faster in 64-bit processor as compared to 32-bit processor.
There are various mapping techniques through which larger RAM is mapped onto the CPU register for faster accessing by the CPU. For 32-bit processors, the Memory Address can be represented using 2^32 bits while using a 64-bit processor the Memory Address can be represented using 2^64 bits.
A 32-bit processor can handle upto 4GB of RAM while on the other side a 64-bit processor can handle up to 16 billion GB of RAM(which is huge).
Why the need to upgrade to a 64-bit processor?
The hard drive is the biggest storage in the computer which can store more than few TeraBytes at this time but it is the slowest of all the memory components. Now the CPU is limited to just 4GB in the case of a 32-bit processor (2^32 addresses) so it can only process just 4GB of data at any given time, which cannot be entirely used by a single program because OS also uses some amount of RAM. To overcome this drawback, we needed to upgrade the power of the CPU for more modern programs like Adobe Photoshop, which require few GB of RAM to run smoothly.
The upgrade was necessary and was understood by Windows which rolled out Windows 7 64-bit and 64-bit driver support which made it most stable OS in that time.
How does my 32-bit Windows run on 64-bit CPU
Because they were made backward compatible as the early CPU were 32-bit mostly, and it had better drivers and more stable than 64-bit counterparts.
Although the 32-bit OS doesn’t fully utilise the full power of CPU, it still works but doesn’t work wonders like 64-bit OS.
In above image, System type shows which architecture processor you are using. So we can know whether 64-bit OS needs to be installed or we can keep using the 32-bit OS.