Processor, OS : 32bit, 64 bit

Let’s try to answer this question by looking at people versus computers; hopefully this will shed some light on things for you:

Things to Keep In Mind

• As amazing as they are, computers are very, very dumb.

Memory

• People have memory (with the exception, arguably, of husbands and politicians.) People store information in their memory for later use.
  • With a question (e.g, “What is your phone number?”) a person is able to retrieve information to give an answer (e.g., “867-5309”)
• All modern computers have memory, and store information in their memory for later use.
  • Because computers are dumb, they can only be asked a very specific question to retrieve information: “What is the value at X in your memory?”
    • In the question above, X is known as an address, which can also be called a pointer.

So here we have a fundamental difference between people and computers: To recall information from memory, computers need to be given an address, whereas people do not. (Well in a sense one could say “your phone number” is an address because it gives different information than “your birthday”, but that’s another conversation.)

Numbers

• People use the decimal number system. That means for every digit in a decimal number, the digit can be one of 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9. People have ten options per digit.
• All modern computers use the binary number system. That means for every digit in a binary number, the digit can only be either 1 or 0. Computers have two options per digit.
  • In computer jargon, a single binary digit is called a bit, short for binary digit.

Addresses

• Every address in a computer is a binary number.
• Every address in a computer has a maximum number of digits (or bits) that it can have. This is mostly because the computer’s hardware is inflexible (also known as fixed) and needs to know ahead of time that an address will only be so long.
• Terms like “32-bit” and “64-bit” are talking about the longest address for which a computer can store and retrieve information. In English “32-bit” in this sense means “This computer expects instructions about its memory to have addresses no more than 32 binary digits long.”
  • As you can imagine, the more bits a computer can handle the longer the address it can look up and therefore the more memory it can manage at one time.

32-bit v. 64-bit Addressing

• For an inflexible (fixed) number of digits (e.g. 2 decimal digits) the possible numbers you can represent is called the range (e.g. 00 to 99, or 100 unique numbers). Adding an additional decimal digit multiplies the range by 10 (e.g. 3 decimal digits -> 000 to 999, or 1000 unique numbers).

• This applies to computers, too, but because they are binary machines instead of decimal machines, adding an additional binary digit (bit) only increases the range by a factor of 2.

  Addressing Ranges:

  • 1-bit addressing lets you talk about 2 unique addresses (0 and 1).
  • 2-bit addressing lets you talk about 4 unique addresses (00, 01, 10, and 11).
  • 3-bit addressing lets you talk about 8 unique addresses (000, 001, 010, 011, 100, 101, 110, and 111).
  • and after a long while… 32-bit addressing lets you talk about 4,294,967,296 unique addresses.
  • and after an even longer while… 64-bit addressing lets you talk about 18,446,744,073,709,551,616 unique addresses. That’s a LOT of memory!

Implications

What all this means is that a 64-bit computer can store and retrieve much more information than a 32-bit computer. For most users this really doesn’t mean a whole lot because things like browsing the web, checking email and playing Solitaire all work comfortably within the confines of 32-bit addressing. Where the 64-bit benefit will really shine is in areas where you have a lot of data the computer will have to churn through. Digital signal processing, gigapixel photography and advanced 3D gaming are all areas where their massive amounts of data processing would see a big boost in a 64-bit environment.