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)