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There was a lot of buzzing (still is) around here lately about 64 bit - from processors to programming for 64 bit machines. So I decided to write a small post on this topic. There are tons of articles out there, so feel free to Yahoo or Google them and read the one you like.

First of, I don't want to write pages and pages about the subject, so consider this just a short introduction. Visit the links I post and if you still need more info, ask. I will provide if I can.

Computers work with BITs (binary digits). A BIT is either 0 (zero) or 1 (one). This basically comes from electrical circuits where you have 0 (zero, off - no electricity) or 1 (one, on - we have power!). You can think at your light switcher. When the light is on, the light bulb is in the state of "1" (on). When you turn it off, its state is 0 (off). Using this technology is similar to the Morse Code, when depending if the light is on or of, and how long it stays in that state, you can send a message on a large distance without any type of wire. Now imagine that your PC has a LOT of tiny little light bulbs that change from 0 to 1 and back, depending on the data that you want to send.

(NOTE: This is just a newbie introduction. If you want to find out How PCs work, check out http://www.howstuffworks.com/pc.htm and their entire website about computers: http://computer.howstuffworks.com/).

"32 bit computer" basically means that the PC uses 32 bits ("light bulbs") to communicate, whereas 64 bit PCs have 64 "light bulbs". You can surely imagine that by sending 64 pieces of information (32 bits x 2) instead of just 32 means (usually) half of the required time to communicate the same thing. So this is advantage number 1 - increased performance.

The second most obvious remark is that if you want to send a word that is larger than 32 characters (assuming we have 1 bit for 1 letter), you need to send more messages just to transmit 1 word. If you have 64 bits, you can send up to two 32 words in the same 64 bit word, which again means double performance. And increased word capacity - advantage number 2.

(I only hope someone will appreciate the efforts I had to put up with in order to write this newbie introduction to bits ...)

More technical part now:

There are two types of 64 bit processors: true 64 bit processors and processors that support 64 bit operations.

To make this clear from the start, all AMD64 and Intel Core2/Quad/Extreme/Xeon support 64 bit operations and you can (it's even recommended) to use a 64 bit operation system with them. There are some "true 64 bit processors" which are, of course, expensive and rare. You do not need a "true 64 bit processor" unless you are Bill Gates and have a lot of money to spend on creating new 64 bit software for your "true" machine. Some of the names of these "true 64 bit processor" (oops, did I write that again? :) ) are: Itanium and Itanium 2 from Intel , and Opteron from AMD.

What is the difference between the two ("supported 64" and "true 64")? You cannot run any 32 bit application on a "true" 64, but you have no problem running either 32 or 64 bit applications on a processor that "supports" 64 bit operations. Itanium and Opteron are heavy duty workstation processors, that will run with dedicated applications which are developed especially for them, so they are not built for running your favorite game on it.

FYI: If you want to have a 64 bit system, you must also buy 64 bit compatible hardware for your processor to work with. Elsewhere, you will just end up with a very smart brain in a much to small case...

Advantages of having a 64 bit architecture?

1. Increased performance due to larger word length
2. Increased performance due to larger BUS size
3. Ability to work with larger memory blocks -> more RAM (up to 16TB) compared to up to 3GB in 32 bit systems
   

1. Need to buy new hardware for it to fully function (although if you already have a Core 2/Quad/Extreme processor, you are most likely already equipped for 64 bit operations)
2. ...

1. Very expensive
   
2. Does not have 32 bit backwards compatibility
3. Applications need to be compiled specially for those types of platforms (you need to rebuild your existing code if migrating from 32/64 to true 64)
4. Very few application which are true 64 bit
   

• 64 bit in general

• 64 bit programming