1: Introduction to Pulses and the International Year of Pulses
1 Microprocessor speeds Measure of system clock speed –How many electronic pulses the clock...
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1 Microprocessor speeds • Measure of system clock speed – How many electronic pulses the clock produces per second (clock frequency) – Usually expressed in frequency (unit Hz) 1 Hz = 1 cycle / second • Kilohertz (KHz), Megahertz (MHz), Gigahertz (GHz) – Or how much time for each cycle: clock cycle time clock cycle time = 1 / clock frequency Second, millisecond, microsecond, nanosecond • Comparison of clock speed only meaningful between identical microprocessors
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Transcript of 1 Microprocessor speeds Measure of system clock speed –How many electronic pulses the clock...
1
Microprocessor speeds• Measure of system clock speed
– How many electronic pulses the clock produces per second (clock frequency)
– Usually expressed in frequency (unit Hz)1 Hz = 1 cycle / second
• Kilohertz (KHz), Megahertz (MHz), Gigahertz (GHz)
– Or how much time for each cycle: clock cycle time clock cycle time = 1 / clock frequency
Second, millisecond, microsecond, nanosecond
• Comparison of clock speed only meaningful between identical microprocessors
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Other performance measures
• Millions of Instructions per Second (MIPS)– High-speed personal computers can perform
over 500 MIPS– Typically a more accurate measure of
performance than clock speed
• Megaflop: one million floating-point operations– Measures ability of computer to perform
complex mathematical operations
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Types of microprocessors• Microprocessor
• Intel makes a family of processors– Pentium III and Pentium4 processors in most PCs– Celeron processor sold for low-cost PCs– Xeon and Itanium for high-end workstations and network servers
• Other processors– AMD make Intel-compatible microprocessors– PowerPC chips used primarily in Macintosh computers– Compaq’s Alpha microprocessor used in high-end servers
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Factors to CPU performance• Size of word Larger word mean more information can be processed
by each instruction
• Fast system frequency means more instructions can be done in a unit of timeor equivalently short clock cycle time means each instruction can be done an short time
• Small number of clock cycles for each instruction
more instruction can be done in a unit time
• Power consumption
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Silicon technology
• The size of a transistor– New technology makes the size of a transistor smaller
and smaller!
– Unit used to measure the size
– Majority: 0.13 micro meter or 130 nano meterMoving to 0.09 micro meter or 90 nano meterAdvanced: 65 nano meters Next a year: 45 nano metersLimit 10 nano meter?
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Processor trends• The numbers of transistors in a CPU
• Word size • Frequency
• Number of processors on a chip
• Voltage
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Factors of system performance
• CPU speed
• Memory size
• Front bus speed
• Access speed to storage
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Storage hierarchy
• Register
• Cache
• Main memory
• Secondary storage, such hard drive
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Cache
• A temporary storage area
– Speeds up data transfer within computer
• Processor cacheControl Unit
ALU
Registers
Memory
CPU
Cache L1
Cache L2
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Processor cache• A small block of high-speed memory
– Stores most frequently and most recently used data and instructions
• Microprocessor looks for what it needs in cache first– Transferred from cache much faster than from memory– If not in cache, control unit retrieves from memory
• The more cache “hits” the faster the system performance
• Internal (Level 1) cache built into microprocessor– Fastest access, but highest cost
• External (Level 2) cache on separate chip– Incorporated into processor on some current microprocessors
