Not so long ago, some 10 years or so, a very important revolution happened: we moved from 16bit applications to 32bit ones. Little by little, overcoming some problems on the way, we carried out this transaction starting with Windows for Workgroups 3.11 and Windows 95, and finishing with the newer versions. Most of you do remember this process very well, I suppose, as well as the fact that this change didn’t bring any tangible performance improvements. So, when we move from 32bit to 64bit, the situation will be just the same.

Now that we have already made a pretty optimistic introduction, let’s try to figure out why everything goes this particular way. Moreover, we suggest checking if the situation is really like we have just described, or maybe we have an erroneous vision of the things. Especially, since the marketing people have created a great stir around 64bit processors, which grows bigger and bigger as we get closer to their launch. It is remarkable, that we have never seen anything like that before, although 64bit RISC chips arrived in the late 90s already. Well, maybe those first ones were strictly server processors, which have been already very well known to a limited number of specialists, that’s why the public response was not that tremendous. And today we have Intel investing many millions of dollars into the marketing of this particular field.

As a result, Intel’s aggressive marketing campaign sometimes creates weird myths and makes the users imagine very strange things about the reality, such as doubling of the systems performance once the transaction to 64bit is complete. Although there is nothing really bad about it: the 64bit processors are still used strictly in servers and powerful workstations. And the people who work with this hardware usually know very well what they need and what the real potential of the equipment is.

Nevertheless, the situation changes. When Athlon 64 arrives, 64bit processors will be considered as a PC solution. That is why, we think it could be a good idea to recall everything we know about these CPUs, their functioning and to separate some myths from true facts.

At first we would like to discuss the very basics of the CPU functioning, as the entire ongoing story will have to do with the basic notions, of course. CPUs have a pretty long history. It starts with the times of Intel 4004, which was a 4bit processor. It means that the general purpose processor registers could save only 4bit numbers, the ALU (arithmetic logic unit) working with the integers could work with them, and the CPU could use 4bit numbers when addressing the memory blocks. In other words, the instructions working with integers could use the values lying between -7 and 8. Well, this is too little for any arithmetic operation, don’t you think so?

However, very soon an 8bit 8008 processor came out (it could use the numbers in the interval from -127 to 128). After that they introduced 16bit 8086 processor (the interval included integers from -32767 to 32768). And in 1986 we all saw the 80386 processor, which was the first one to support 32bit work mode and hence to deal with integers exceeding 2 billion. By the way, do you have any idea what work we are talking about when we discuss these integers?