da riko » ven mag 27, 2005 3:13 pm
Da wikipedia:
The clock rate is the fundamental rate in cycles per second, measured in hertz, at which a computer performs its most basic operations such as adding two numbers or transferring a value from one processor register to another. Different chips on the same computer motherboard may have different clock rates. Usually when referring to a computer, the term "clock rate" is used to refer to the speed of the CPU.
The clock rate of a CPU is normally determined by the frequency of an oscillator crystal. The original IBM PC, circa 1981, had a clock rate of 4.77 MHz (4,770,000 cycles/second). In 1995, Intel's Pentium chip ran at 100 MHz (100 million cycles/second), and in 2002, an Intel Pentium 4 model was introduced as the first CPU with a clock rate of 3 GHz (three billion cycles/second).
The clock rate of a computer is only useful for providing comparisons between computer chips in the same processor family. An IBM PC with an Intel 486 CPU running at 50 MHz will be about twice as fast as one with the same CPU, memory and display running at 25 MHz. However, there are many other factors to consider when comparing the speeds of entire computers, like the clock rate of the computer's front side bus, the clock rate of the memory chips, the width in bits of the CPU's bus, and the amount of Level 1 and Level 2 cache.
Clock rate should not be used when comparing different computers or different processor families. Rather, some software benchmark should be used. Clock rate can be very misleading, since the amount of work different computer chips can do in one cycle varies. For example, RISC CPUs tend to have simpler instructions than CISC CPUs (but higher clock rates), and superscalar processors can execute more than one instruction per cycle.
-enrico
fibs = 0 : 1: [ a + b | (a, b) <- zip fibs (tail fibs) ]
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