Hardware Reference
In-Depth Information
The fact that the IA-64 architecture is not an extension of IA-32 but is instead a new and
completely different architecture was fine for non-PC environments such as servers (for
whichIA-64wasdesigned),butthePCmarkethasalwayshingedonbackwardcompatib-
ility. Even though emulating IA-32 within IA-64 is possible, such emulation and support
is slow.
With the door now open, AMD seized this opportunity to develop 64-bit extensions to
IA-32, which it calls AMD64 (originally known as x86-64). Intel eventually released its
own set of 64-bit extensions, which it calls EM64T or IA-32e mode. As it turns out, the
Intel extensions are almost identical to the AMD extensions, meaning they are software
compatible. It seems for the first time that Intel has unarguably followed AMD's lead in
the development of PC architecture.
However, AMD and Intel's 64-bit processor could only run in 32-bit mode on existing
operating systems. To make 64-bit computing a reality, 64-bit OSs and 64-bit drivers are
also needed. Microsoft began providing trial versions of Windows XP Professional x64
Edition (which supports AMD64 and EM64T) in April 2005, but it wasn't until the re-
leaseofWindowsVistax64in2007that64-bitcomputingwouldbegintogomainstream.
Initially, the lack of 64-bit drivers was a problem, but by the release of Windows 7 x64 in
2009, most device manufacturers were providing both 32-bit and 64-bit drivers for virtu-
ally all new devices. Linux is also available in 64-bit versions, making the move to 64-bit
computing possible for non-Windows environments as well.
Another important development is the introduction of multicore processors from both In-
tel and AMD. Current multicore desktop processors have up to six full CPU cores op-
erating off of one CPU package—in essence enabling a single processor to perform the
work of multiple processors. Although multicore processors don't make games that use
single execution threads play faster, multicore processors, like multiple single-core pro-
cessors,splituptheworkloadcausedbyrunningmultipleapplications atthesametime.If
you'veevertriedtoscanformalwarewhilesimultaneouslycheckingemailorrunningan-
otherapplication, you'veprobablyseenhowrunningmultiple applications canbringeven
the fastest processor to its knees. With multicore processors available from both Intel and
AMD,yourabilitytogetmoreworkdoneinlesstimebymultitaskingisgreatlyenhanced.
Multicore processors also support 64-bit extensions, enabling you to enjoy both multicore
and 64-bit computing's advantages.
PCshavecertainlycomealongway.Theoriginal8088processorusedinthefirstPCcon-
tained 29,000 transistors and ran at 4.77MHz. Compare that to today's chips: The AMD
Phenom II x6 has an estimated 904 million transistors and runs at up to 3.3GHz or faster,
andthesix-core Intel Corei7models havearound1.17million transistors andrunatupto
3.4GHzorfaster.Asmulticoreprocessorswithlargeintegratedcachescontinuetobeused
