Why Windows 7 will be released in 32-bit version

why the Windows OS are not still mostly 64-bit? Take example of the new OS Windows 7 ,,, why Windows 7 will be released in 32-bit version ( why can it be like Mac OS X 10.6 )
Thank you .

First, remember that passage of this type has already taken place on our PC: the 16 to 32 bits. In 1985, Intel announces the 80386, first 32-bit x86 processor, which followed with 80,286 and 8086 (the 186 was very little used in PCs), two 16-bit CPU. Were the first Windows 16-bit and even if Windows 3.11 could use 32-bit code with certain extensions (like the level editor Warcraft II), it was coded in 16 bits. Windows 95 was the first to require a Windows 32-bit processor but it still contained a lot of 16-bit codes.

In practice, the first Windows general public did not have a code was 16 bit Windows XP (or NT 4.0 or Windows 2000 are regarded as public OS). It was therefore necessary to wait 14 years to abandon the 16-bit OS. In practice, Windows XP still runs 16-bit programs, only 64-bit versions of Windows do not allow more. As shown, the task is long.

The 64-bit x86 processors is still a relatively new technology: the first compatible processor in April 2003 and was intended for the professional market (Opteron) and the massive 64-bit processors in the general public is only mid-2006 (with apologies to fans of AMD, the Core 2 Duo Intel who actually launched the 64-bit). For 64-bit OS, the arrival of Windows 64-bit version of April 2005, with a Windows XP designed for professionals (based on the code of the server version in 2003).

It was not until Windows Vista (early 2007) for a true Windows 64-bit general public, four years after the first compatible processor, which is already fast.

Windows 7 and Mac OS X 10.6 is planned for 32-bit version. Why 64-bit versions are not the only market? The first reason is simple: there is still a lot of 32-bit processors on the market. Although the Pentium 4 and Core 2 are 64 bit for about 3 years (just like the K8 and K10 in AMD), there are still many 32-bit processors: the K7, some Sempron, some Pentium 4, Celeron some, all Pentium-M and the Core Duo. In addition, a popular processor in 2008, Atom N270, is only 32 bits.

The second reason is the interest of the 64-bit: few programs exist in 64-bit and performance is not significantly better. Moreover, until recently, 4GB were a luxury. Finally, without 64-bit OS, nobody develops in 64 bits, so that no one buys the 64-bit OS.

The third reason comes from the pilot: a 64-bit Windows requires special drivers. For the hardware (say less than three years), there is usually a driver for Vista 64 bit and sometimes a 64-bit driver for XP. For older devices, the pilot is not always. The fact that Windows 7 uses the same drivers as Windows Vista is an advantage: you should not expect a complete rewrite.

The last reason is related to industry, sometimes slow, 64-bit Windows no longer supports the 16-bit code, which can cause problems with older applications.

In fact, even if Windows 7 will accelerate the transition to 64 bits, the 32-bit code is likely to remain so for a long time the norm for programs and it is not even entirely sure that the successor of Windows 7 will be available only 64 bits.

Note that this analysis is limited to Windows, which is a much more dependent on the market that Mac OS X and Linux. For Mac OS X, Snow Leopard OS will be the first 64 bits of the firm (with a 32-bit version for the Core Duo) but his successor will be a priori totally 64 bits, while Linux was the first OS x86 compatible 64-bit and that the major distributions are all 64-bit for a while (which in practice poses fewer problems than Windows).