Processing and Memory - Strata Study Guide - page 9

second. The original IBM PC, released in 1981, operated at 4.77 MHz. Processor speeds
have exponentially increased because then because of new technology advances, with some
of the fastest processors today running at more than 3 GHz.
In Table 1.1, you can see a relative comparison of some single-processor clock speeds.
Notice that the dates end at 2008. That's not a misprint; it's just that dual-core and quad-
core processors have replaced single-processor models in recent years. You'll learn about
those processors later in this chapter.

TABLE 1.1 Comparison of single-processor clock speeds

Speed In Plain Numbers Example Processor Year Available (Estimate)

50 MHz 50,000,000 Intel 486 1993-1995

500 MHz 500,000,000 Intel Pentium 3 1999-2001

1.5 GHz 1,500,000,000 Intel Pentium 4 2000-2003

3 GHz 3,000,000,000 Intel Pentium 4 2005-2008

Don't confuse the number of cycles per second with instructions per second (IPS) , the
number of instructions that a processor can complete per second. Many instructions carried
out by processors take multiple internal clock cycles to execute. Many current systems
compute in millions of instructions per second (MIPS) .
A processor's speed is related to its number of instructions per second, but other factors
besides its speed can affect the number of instructions it can process per second. For
example, a multicore CPU can process more instructions than a single-core, and other
technology enhancements such as hyperthreading and effi cient cache usage further enhance
a processor's capability. As a point of reference, the Intel Core i7 Extreme Edition (quad
core) runs at 3.3 GHz and processes 147,600 MIPS.
Another major contributor to the performance of any processor is the quality and speed
of the motherboard that supports the processor. The motherboard's system bus (also called
the front-side bus ) is the pathway that delivers data to the processor. The speed at which
this pathway operates is determined by the motherboard's front-side bus speed. The system
timer on the motherboard determines this speed. Most motherboards can automatically
adjust the speed of the timer based on the installed processor; on older models, it was
necessary to set jumpers on the motherboard manually to indicate what processor type and
speed was installed.

The word bus as it's used in computers comes from Latin; the original word
was a shorthand version of omnibus or to “transport all.” Here a bus can
literally transport all data.