Play Video
1
clock rate
clock rate
::2010/07/22::
Play Video
2
Computer Performance: Relative Performance, CPU Time, Clock Cycle, Clock Rate
Computer Performance: Relative Performance, CPU Time, Clock Cycle, Clock Rate
::2013/12/17::
Play Video
3
Understanding the CPU for beginners
Understanding the CPU for beginners
::2012/12/30::
Play Video
4
CCNA - Configuring The Clock Rate on Cisco Router.avi
CCNA - Configuring The Clock Rate on Cisco Router.avi
::2010/12/11::
Play Video
5
CLOCK RATE
CLOCK RATE
::2012/09/27::
Play Video
6
Configurando Clock rate no Roteador CISCO
Configurando Clock rate no Roteador CISCO
::2013/08/21::
Play Video
7
Cisco Packet Tracer: Configuração de interface serial, clock rate e senha em roteador
Cisco Packet Tracer: Configuração de interface serial, clock rate e senha em roteador
::2013/04/18::
Play Video
8
Clock rate on a cisco router
Clock rate on a cisco router
::2014/06/14::
Play Video
9
router rip and clock rate By Cheaputheara
router rip and clock rate By Cheaputheara
::2014/04/06::
Play Video
10
BOSS TE 2 TERA ECHO sampling clock rate Modification
BOSS TE 2 TERA ECHO sampling clock rate Modification
::2014/02/16::
Play Video
11
Monitor CPU Clockrate and Temperature
Monitor CPU Clockrate and Temperature
::2014/05/24::
Play Video
12
Setting The Clock Rate.avi
Setting The Clock Rate.avi
::2011/10/14::
Play Video
13
Clock Rate
Clock Rate
::2012/06/15::
Play Video
14
Configuração de interfaces, bandwidth e clock rate (Packet Tracer)
Configuração de interfaces, bandwidth e clock rate (Packet Tracer)
::2010/12/15::
Play Video
15
Mikroprosesor 08: clock rate/frekuensi/clock speed (dasar)
Mikroprosesor 08: clock rate/frekuensi/clock speed (dasar)
::2011/02/01::
Play Video
16
clock rate.mpg
clock rate.mpg
::2011/09/04::
Play Video
17
Understanding CPU Specifications
Understanding CPU Specifications
::2013/01/16::
Play Video
18
Minecraft - összes fajta órajel  - All type of clock rate.
Minecraft - összes fajta órajel - All type of clock rate.
::2014/01/09::
Play Video
19
Wiki Clock rate
Wiki Clock rate
::2013/07/03::
Play Video
20
Lenguaje de señas. "clock rate"
Lenguaje de señas. "clock rate"
::2013/10/28::
Play Video
21
Taiwan G.pulse Heart Rate Monitor-M10 graphic instruction-1st MODE: Clock Mode
Taiwan G.pulse Heart Rate Monitor-M10 graphic instruction-1st MODE: Clock Mode
::2013/09/09::
Play Video
22
How to set rate plan in Clock PMS.
How to set rate plan in Clock PMS.
::2014/03/06::
Play Video
23
SNMP - MIB Browser - 1/3 - Ips, cables, connections and clock
SNMP - MIB Browser - 1/3 - Ips, cables, connections and clock
::2010/12/01::
Play Video
24
Trumeter Rate Meter 8771 Counter Clock Display from Countersales main UK supplier
Trumeter Rate Meter 8771 Counter Clock Display from Countersales main UK supplier
::2012/09/27::
Play Video
25
Minecraft:Redstone Digital Clock
Minecraft:Redstone Digital Clock
::2012/04/06::
Play Video
26
Purchase the Countdown Clocks at an Affordable rate
Purchase the Countdown Clocks at an Affordable rate
::2014/03/27::
Play Video
27
15. Rates in Clock Evolution 2011 Hotel Software - Simple rate
15. Rates in Clock Evolution 2011 Hotel Software - Simple rate
::2013/02/12::
Play Video
28
Worlds Biggest Alarm Clock,,,please rate
Worlds Biggest Alarm Clock,,,please rate
::2009/08/11::
Play Video
29
RTE 9 O
RTE 9 O'Clock News, 23rd July 2010, PTsb Rate Hike
::2010/07/26::
Play Video
30
THE LINE: Utility Rate Hikes/On the Clock (2011-06-10)
THE LINE: Utility Rate Hikes/On the Clock (2011-06-10)
::2011/06/11::
Play Video
31
BBC Six o
BBC Six o'clock news Maastricht treaty and Exchange Rate Mechanism problems 1993
::2009/10/15::
Play Video
32
Stable 3-clock with Variable Pulse Rate.mkv
Stable 3-clock with Variable Pulse Rate.mkv
::2011/07/14::
Play Video
33
Prestigio Multiphone 5505 DUO - Prezentare
Prestigio Multiphone 5505 DUO - Prezentare
::2014/10/01::
Play Video
34
Minecraft fast rate noteblocks from above
Minecraft fast rate noteblocks from above
::2011/01/20::
Play Video
35
Trumeter 9100 digital counter clock and rate meter from Countersales the main UK supplier
Trumeter 9100 digital counter clock and rate meter from Countersales the main UK supplier
::2012/09/17::
Play Video
36
CHECK THE RATE OF CLOCK  DEADBEAT ESCAPEMENT
CHECK THE RATE OF CLOCK DEADBEAT ESCAPEMENT
::2011/10/15::
Play Video
37
Make Your Own LEGO Clock (Redux)
Make Your Own LEGO Clock (Redux)
::2013/05/27::
Play Video
38
Rate of Reaction of Sodium Thiosulfate and Hydrochloric Acid
Rate of Reaction of Sodium Thiosulfate and Hydrochloric Acid
::2012/12/20::
Play Video
39
Coldplay Clocks lyrics
Coldplay Clocks lyrics
::2012/01/30::
Play Video
40
Clock Tuner (See how to adjust a clock)
Clock Tuner (See how to adjust a clock)
::2013/02/05::
Play Video
41
MissionCriticalPerformanceSQL2014
MissionCriticalPerformanceSQL2014
::2014/02/08::
Play Video
42
High-Performance time-dependent Lattice Boltzmann Navier-Stokes flow on GPU !
High-Performance time-dependent Lattice Boltzmann Navier-Stokes flow on GPU !
::2012/03/21::
Play Video
43
how to set an alarm clock on a mac
how to set an alarm clock on a mac
::2013/09/23::
Play Video
44
Sweeping Demo
Sweeping Demo
::2014/01/18::
Play Video
45
ACER Liquid E1 (ITA)
ACER Liquid E1 (ITA)
::2014/03/01::
Play Video
46
Iodine Clock (slow motion) - Periodic Table of Videos
Iodine Clock (slow motion) - Periodic Table of Videos
::2013/01/18::
Play Video
47
Ivee Voice Activated Digital Talking Alarm Clock Review
Ivee Voice Activated Digital Talking Alarm Clock Review
::2013/02/05::
Play Video
48
Samsung Galaxy Note 800 hands on review
Samsung Galaxy Note 800 hands on review
::2013/04/21::
Play Video
49
cisco Confuguration
cisco Confuguration
::2011/08/21::
Play Video
50
Insignia Clock Review
Insignia Clock Review
::2009/06/25::
NEXT >>
RESULTS [51 .. 101]
From Wikipedia, the free encyclopedia
  (Redirected from Clock frequency)
Jump to: navigation, search

The clock rate typically refers to the frequency at which a CPU is running. It is measured in the SI unit hertz.

Details[edit]

The clock rate of a CPU is normally determined by the frequency of an oscillator crystal. Typically a crystal oscillator produces a fixed sine wave—the frequency reference signal. Electronic circuitry translates that into a square wave at the same frequency for digital electronics applications (or, in using a CPU multiplier, some fixed multiple of the crystal reference frequency). The clock distribution network inside the CPU carries that clock signal to all the parts that need it. An AD Converter has a "clock" pin driven by a similar system to set the sampling rate. CPU manufacturers typically charge premium prices for CPUs that operate at higher clock rates, a practice called binning. For a given CPU, the clock rates are determined at the end of the manufacturing process through actual testing of each CPU. CPUs that are tested as complying with a given set of standards may be labeled with a higher clock rate, e.g., 1.50 GHz, while those that fail the standards of the higher clock rate yet pass the standards of a lesser clock rate may be labeled with the lesser clock rate, e.g., 1.3 GHz, and sold at a lower price.[1] Chip manufacturers publish a "maximum clock rate" specification, and they test chips before selling them to make sure they meet that specification, even when executing the most complicated instructions with the data patterns that take the longest to settle (testing at the temperature and voltage that runs the lowest performance).

With any particular CPU, replacing the crystal with another crystal that oscillates half the frequency ("underclocking") will generally make the CPU run at half the performance and reduce waste heat produced by the CPU. Conversely, some people try to increase performance of a CPU by replacing the oscillator crystal with a higher frequency crystal ("overclocking").[2] However, the amount of overclocking is limited by the time for the CPU to settle after each pulse, and by the extra heat created.

After each clock pulse, the signal lines inside the CPU need time to settle to their new state. That is, every signal line must finish transitioning from 0 to 1, or from 1 to 0. If the next clock pulse comes before that, the results will be incorrect. In the process of transitioning, some energy is wasted as heat (mostly inside the driving transistors). When executing complicated instructions that cause many transitions, the higher the clock rate the more heat produced. Transistors may be damaged by excessive heat.

Historical milestones and current records[edit]

The first electromechanical general purpose computer, the Z3 operated at a frequency of about 5–10 Hz. The first electronic general purpose computer, the ENIAC, used a 100 kHz clock in its cycling unit. As each instruction took 20 cycles, it had an instruction rate of 5kHz.

The first commercial PC, the Altair 8800 (by MITS), used an Intel 8080 CPU with a clock rate of 2 MHz (2 million cycles/second). The original IBM PC (c. 1981) had a clock rate of 4.77 MHz (4,772,727 cycles/second). In 1992, both Hewlett-Packard and Digital Equipment Corporation broke the difficult 100 MHz limit with RISC techniques in the PA-7100 and AXP 21064 DEC Alpha respectively. In 1995, Intel's P5 Pentium chip ran at 100 MHz (100 million cycles/second). In March 6, 2000, AMD reached the 1GHz milestone a few months ahead of Intel. In 2002, an Intel Pentium 4 model was introduced as the first CPU with a clock rate of 3 GHz (three billion cycles/second corresponding to ~3.0×10−10seconds or 0.3 nanoseconds per cycle). Since then, the clock rate of production processors has increased much more slowly, with performance improvements coming from other design changes. A nano second is the time for light or an electric-signal to travel a distance of about 30cm, coming close to the distances a signal travels in the computer.

As of 2011, the Guinness Record for fastest CPU is by AMD with a Bulldozer based FX chip "overclocked" to 8.805 GHz; however, whilst the next generation of AMD's FX chips "Piledriver" with a clock rate of 8.670 GHz.[3]

As of mid-2013, the highest clock rate on a production processor is the IBM zEC12, clocked at 5.5 GHz, which was released in August of 2012.

Research[edit]

Engineers continue to find new ways to design CPUs that settle a little more quickly or use slightly less energy per transition, pushing back those limits, producing new CPUs that can run at slightly higher clock rates. The ultimate limits to energy per transition are explored in reversible computing, although no reversible computers have yet been implemented.

The first fully reversible CPU, the Pendulum, was implemented using standard CMOS transistors in the late 1990s at MIT.[4][5][6][7]

Engineers continue to find new ways to design CPUs so that they complete more instructions per clock cycle (achieving a lower CPI count), although it may run at the same or a lower clock rate as older CPUs. This is achieved through architectural techniques such as instruction pipelining and out-of-order execution which attempts to exploit instruction level parallelism in the code.

See also: Moore's law

Comparing[edit]

Main article: Megahertz myth

The clock rate of a CPU is most useful for providing comparisons between CPUs in the same family. The clock rate is only one of several factors that can influence performance when comparing processors in different families. For example, an IBM PC with an Intel 80486 CPU running at 50 MHz will be about twice as fast (internally only) as one with the same CPU and memory running at 25 MHz, while the same will not be true for MIPS R4000 running at the same clock rate as the two are different processors that implement different architectures and microarchitectures. There are many other factors to consider when comparing the performance of CPUs, like the width of the CPU's data bus, the latency of the memory, and the cache architecture.

The clock rate alone is generally considered to be an inaccurate measure of performance when comparing different CPUs families. Software benchmarks are more useful. Clock rates can sometimes be misleading since the amount of work different CPUs can do in one cycle varies. For example, superscalar processors can execute more than one instruction per cycle (on average), yet it is not uncommon for them to do "less" in a clock cycle. In addition, subscalar CPUs or use of parallelism can also affect the performance of the computer regardless of clock rate.

See also[edit]

External Links[edit]

References[edit]

  1. ^ [1] [2]
  2. ^ "Overclocking" early processors was as simple – and as limited – as changing the discrete clock crystal ... The advent of adjustable clock generators has allowed "overclocking" to be done without changing parts such as the clock crystal."-- Overclocking Guide Part 1: Risks, Choices and Benefits : Who Overclocks? by Thomas Soderstrom
  3. ^ Chiappetta, Marco (23 September 2011). "AMD Breaks 8GHz Overclock with Upcoming FX Processor, Sets World Record". HotHardware. Retrieved 2012-04-28. 
  4. ^ Michael Frank. "RevComp - The Reversible and Quantum Computing Research Group".
  5. ^ Michael Swaine. "Backward to the Future". Dr. Dobb's Journal. 2004.
  6. ^ Michael P. Frank. "Reversible Computing: A Requirement for Extreme Supercomputing".
  7. ^ Matthew Arthur Morrison. "Theory, Synthesis, and Application of Adiabatic and Reversible Logic Circuits For Security Applications". 2014.

This article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later.

Wikipedia content is licensed under the GFDL License
Powered by YouTube
LEGAL
  • Mashpedia © 2014