Saturday, February 23, 2013

Processor Speed

Processor Speed

Processor Speed

A tractor can go 12 miles per hour (mph), a minivan can go 90 mph, and a drag racer can go 220 mph. These speeds, however. provide little insight into the relative capabilities of these vehicles. What good is a 220-mph tractor or a 12-mph minivan? The same is true of computers. Generally, micros are measured in MHZ; workstations, minis, and mainframes are measured in MIPS; and supercomputers in FLOPS.

Megahertz: MHz A crystal oscillator paces the execution of instructions within the processor of a microcomputer. A micro's processor speed is rated by its frequency of oscillation, or the number of clock cycles per second. Most personal computers are rated between 5 and 100 mega. hertz, or MHz (millions of clock cycles). The elapsed time for one clock cycle is l/frequency (1 divided by the frequency). For example, the time it takes to complete one cycle on a 50-Mllz processor is 1150,000,000, or 0.00000002 seconds, or 20 nanoseconds. Normally several clock cycles arc required to fetch, decode, and execute a single program instruction The shorter the clock cycle, the faster the processor.

To properly evaluate the processing capability of a micro. you must consider both the processor speed and the word length. A 32-bit micro with a 50-MHz processor has more processing capability than a 16-bit mi­cro with a 50-Mllz processor.

We seldom think in time units of less than a second; consequently. it is almost impossible for us to think in terms of computer speeds. Imagine,today's microcomputers can execute more instructions in a minute than the number of times your heart has beaten since the day you were born!

MIPS The processing speed of today's workstations, minis, and main­frames is often measured in MIPS, or millions of instructions per second These computers operate in the 20 to 1000 MIPS range. A 100-MIPS com­puter can execute 100 million instructions per second. Now that comput­ers arc performing at 1000 MIPS, look for BIPS (billions of instructions per second) to emerge as a measure of speed on high-end mainframe computers .

FLOPS Supercomputer speed is measured in FLOPS (rhymes with plops)-floating point operations per second. Supercomputer applications, which are often scientific. frequently involve floating point operations. Floating point operations accommodate very small or very large numbers State-of-the-an supercomputers operate in the 30 to 100 GFLOPS range GFLOPS (gigaflops) refers to a billion FLOPS.

MEMORY BITS Processor Description

• Word length: Bits handled As a unit

• Speed (micros): MHz (Clock cycles)

• Speed (workstations, minis, mainframes): MIPS

• Speed (supercomputers):

FLOPS, GFLOPS

• Capacity:

kilobyte (KB)

kilobit (Kb)

megabyte (MB)

megabit (Mb)

gigabyte (GB)

terabyte(TB)