Hardware Reference
In-Depth Information
Another important development is the introduction of multicore processors from both Intel and AMD.
Current multicore desktop processors from Intel and AMD have up to eight full CPU cores operating
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 processors, split up the workload caused by
running multiple applications at the same time. If you've ever tried to scan for malware while
simultaneously checking email or running another application, you've probably seen how running
multiple applications can bring even the fastest processor to its knees. With multicore processors
available from both Intel and AMD, your ability to get more work done in less time by multitasking is
greatly enhanced. A growing number of applications are now optimized for multicore processors;
these applications are known as
multithreaded applications
. Multicore processors also support 64-
bit extensions, enabling you to enjoy both multicore and 64-bit computing's advantages.
PCs have certainly come a long way. The original 8088 processor used in the first PC contained
29,000 transistors and ran at 4.77MHz. Compare that to today's chips: The AMD eight-core FX-8000
has an estimated 1.2 billion transistors and runs at up to 3.6GHz standard speed (4.2GHz in Turbo
Core mode), and high-end six-core Intel Core i7 models have around 2.27 billion transistors and run
at up to 3.4GHz or faster. As multicore processors with large integrated caches continue to be used in
designs, look for transistor counts and real-world performance to continue to increase well beyond a
billion transistors. And the progress won't stop there, because according to Moore's Law, processing
speed and transistor counts are doubling every 1.5-2 years.
Processor Specifications
Many confusing specifications often are quoted in discussions of processors. The following sections
discuss some of these specifications, including the data bus, address bus, and speed. The next section
includes a table that lists the specifications of virtually all PC processors.
Processors can be identified by two main parameters: how wide they are and how fast they are. The
speed of a processor is a fairly simple concept. Speed is counted in megahertz (MHz) and gigahertz
(GHz), which means millions and billions, respectively, of cycles per second—and faster is better!
The width of a processor is a little more complicated to discuss because three main specifications in
a processor are expressed in width:
• Data (I/O) bus (also called FSB or front side bus)
• Address bus
• Internal registers
Note that the processor data bus is also called the
front side bus
(FSB),
processor side bus
(PSB), or
just
CPU bus
. All these terms refer to the bus that is between the CPU and the main chipset
component (North Bridge or Memory Controller Hub). Intel uses the FSB or PSB terminology,
whereas AMD uses only FSB. I usually just like to say
CPU bus
in conversation or when speaking
during my training seminars, because that is the least confusing of the terms while also being
completely accurate.
The number of bits a processor is designated can be confusing. Most modern processors have 64-bit
(or wider) data buses; however, that does not mean they are classified as 64-bit processors.
Processors from the 386 through the Pentium 4 and Athlon XP are considered 32-bit processors
because their internal registers are 32 bits wide, although their data I/O buses are 64 bits wide and
