Это видео недоступно.
Сожалеем об этом.
Clock Speeds and Bus Speeds
HTML-код
- Опубликовано: 16 авг 2024
- In this video from ITFreeTraining I will look at how a computer generates a clock rate and how this is used with different devices like the CPU and buses. Understanding this will give you a better understanding of how different devices work with each other, even when they run at different speeds.
Download the PDF handout: itfreetraining....
Cycle
0:17 Before I start looking at how a computer generates a clock rate, I will first look at the concept of a cycle. A cycle in a computer is the smallest time period a computer can perform a function in. To understand how it works, consider that you have a conveyor belt.
On the conveyor belt are the instructions the computer will process. Some instructions take one cycle. Other instructions take more than one cycle. In this example, the divide instruction takes two cycles where the add and subtract instructions take one each.
In order to run the conveyor belt, something needs to drive it, in this case a cog. The computer will process instructions based essentially on how quickly the cog turns. The faster the cog turns, the faster the computer will run. Keep in mind that if you run the conveyor too quickly, this will lead to errors in processing. So, the next point to consider is - how does a computer turn the cog, so to speak?
Crystal Oscillator
1:14 On your motherboard there will be one or more crystal oscillators. They come in different shapes and sizes, but with computers they generally tend to be a rectangular component with rounded corners soldered onto the motherboard.
The crystal oscillator gets its name because it contains an actual crystal. The crystal used is generally quartz. When electricity is applied to the crystal, it vibrates. The crystal will vibrate at a precise frequency which is used to create an electrical signal. Oscillators don’t run very quickly. The speed of them is measured in megahertz, so the question is - how does a high clock rate get generated?
Clock Speeds
1:52 Before I look at how this is achieved, I will first look at how the clock rate is measured. One clock cycle is one hertz. One megahertz is a million cycles per second and one gigahertz is a billion cycles per second.
Crystal oscillators run in the low megahertz range and generally computers use crystal oscillators that run below 100 megahertz. A common speed for a crystal used in computing is 14.318 MHz, which compared to the rest of the computer is not too fast. So let’s look at how gigahertz clock rates are created.
Clock Generator
2:30 The crystal in your computer generates a signal. This signal goes to a chip on the motherboard which uses the signal from the crystal to create other frequencies. It is beyond the scope of this video to go into too much detail about how this is done and there a number of different methods, but essentially one method is to look at the rise and fall of the signal. Looking at how high or low the signal is can be used to generate other clock rates. These are used for devices like the North Bridge and PCI Express slots amongst others. In some cases, a second crystal oscillator may be used to generate speeds for other buses. This however does not include the CPU clock rate. Let’s have a look at how that is generated.
CPU Clock Rate
3:15 The CPU runs faster than any other component in the computer. This causes some problems when generating a clock rate. The biggest problem is that, if a chip external to the CPU were to generate the clock rate, given the extra distance between the chip and the CPU, this will increase the probability there will be corruption in the clock signal. Having a good reliable clock rate is essential to the CPU running at high speed and thus cannot be generated by an external chip.
To get around this, the North Bridge will generate a slower clock rate than the one the CPU runs at. This slower clock rate will be sent to the CPU. This clock rate will be the speed of the front side bus. Once the clock rate reaches the CPU, a clock generator in the CPU will generate its own clock rate. This clock rate is based on a multiplier. The multiplier will be configured in the BIOS. Most BIOS will automatically detect the multiplier, but you can change it if you wish.
Multipliers vary from CPU to CPU, but it is not uncommon for a multiplier to be as high as ten. Since the multiplier is linked to the front bus speed, the faster the front side bus the lower the multiplier will be.
Description to long for RUclips. Please see the following link for the rest of the description. itfreetraining....
References
“The Official CompTIA A+ Core Study Guide (Exam 220-1001)” Chapter 3 Position 6828-6925
“Crystal oscillator” en.wikipedia.o...
Credits
Trainer: Austin Mason ITFreeTraining.com
Voice Talent: HP Lewis hplewis.com
Quality Assurance: Brett Batson www.pbb-proofre...
![Chuckyy - Devil Hours [Official Music Video]](http://i.ytimg.com/vi/f3wZGj0VnZU/mqdefault.jpg)
The most accurate explanation of clock speed. Thanks
Glad it was helpful!
Very cool and explained concisely for layman's such as myself. Thanks
going through the video is helpful. I take my A+ cert in April. I hope this helps as the book is very long readings with short questions at the end. Need a simpler term to grasp the concepts. I will be watching serveral times until I take my test. Thanks
How did it go?
How did it go?
Hope you passed.
Absolutely brilliant description. Many thanks
Glad it was helpful!
The Best ,the simplest and easy 🌹🙏informative course covers all aspects needed .thanks
Glad you liked it
The explanations were very clear and thank you so much 👍
Glad to hear that!
Busy with A+ and this helped a lot, thanks!
Glad it helped!
On the new computers that we don't have the north bridge chipset, which device will pass the clock Cycles to the CPU?
Modern motherboards the clock signal is generated by the dedicated chip on the motherboard rather than by a traditional north bridge chip.
Thank you 🙏
You’re welcome 😊
Very informative. I wish I found this channel earlier .. where can I find other courses ? I have my A+ exam next month
We are only working on A+ at present. Hope you passed your exam.
thank for this video
No problem. Thanks for watching.
I want to understand the complete hardware sturcture and architecture of the computer do you any specific playlist for it , most likely related to microprocessors
We don't have any playlists for that, however, some of our videos cover those topics, but not in a great deal of detail.
Love the explication! Do you provide courses online?
We are in the process of completing the course. All the videos for it will be available on RUclips or the web site.
Tq sir
Thanks for watching.
I am looking up information on RLL
RLL Run-length limited. We unfortunately don't have any videos on that topic.
Hello,
Like many here I am studying for my A+ and I am unclear as to what, exactly, the system bus consists of in this context? The authors of various books seem to use the terms "system bus" and "FSB" interchangeably in come contexts and different in others with respect to speed. As a real world example, if I use CPUID it lists my motherboard's bus speed at 99.80 MHz. Hypothetically, if I had an FSB would it also run at that speed?
So Front Side Bus (FSB) was a bus used in Intel CPU to connect the CPU to the north bridge. AMD used something else and Intel later change to HyperTransport, Intel QuickPath Interconnect and Direct Media Interface.
The computer has a number of different buses. Since FSB was popular for a while the main bus going from the CPU may sometimes be referred (Incorrectly by some) to a FSB even though it use a different technology. When you used CPUID or other software, the bus it is referring to will be the fastest and biggest bus which is connecting to the CPU. In older CPU's it connected to the north bridge which contains the memory controller. When the memory controller got moved in the CPU there was no north bridge any more, thus the bus from the CPU go straight to the memory modules and other components.
This was uploaded a few months ago, but you refer to the north bridge what's component parts were largely moved to the CPU?
It would be difficult to find a motherboard with a Northbridge now days on the market. However the CompTia exam still talks about it. Also consider that if you are fixing an old computer it most likely will have a Northbridge. Memory controller and high speed devices generally have been moved into the CPU.
@@itfreetraining True, great points
Best explanation!!
Glad you think so!
🎉🎉🎉
Thanks for watching.
Gear explanation gd but can also be bit in detail.
What other information did you want to see?
@@itfreetrainingThe proper flow , I knew only bit and pieces.
How clock signal makes cpu to fetch - decode- execute. What type of assemble programs used to make processor process , how data taken from registers- memory, how I/p , o/p peripherals interfaces.
What each pin set in a processor does. On the whole an eg of a modern processor Architecture & pin structure and what each pin used with animation explanation will help me a lot.
I know it's too much but it will be easy for me to watch & grasp than learning myself😉☺️