Aa.....
Sir Bus Speed Or Cashe Memory Kiya Hae....plz Detail Say Bata
Dean......or In Ka Kaam Bhi Kay Yeh Kiya Kiya Kaam Akratay.......
Thanx... Alot....... Take Good Care ....
merai khayll mai ap it ki student hai
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Bus Speed
A bus is simply a circuit that connects one part of the motherboard to another. The more data a bus can handle at one time, the faster it allows information to travel. The speed of the bus, measured in megahertz (MHz), refers to how much data can move across the bus simultaneously.
ap ab zara tsweer ko daikooo
Busses connect different parts of the motherboard
to one another
Bus speed usually refers to the speed of the front side bus (FSB), which connects the CPU to the northbridge. FSB speeds can range from 66 MHz to over 800 MHz. Since the CPU reaches the memory controller though the northbridge, FSB speed can dramatically affect a computer's performance.
Here are some of the other busses found on a motherboard:
* The back side bus connects the CPU with the level 2 (L2) cache, also known as secondary or external cache. The processor determines the speed of the back side bus.
* The memory bus connects the northbridge to the memory.
* The IDE or ATA bus connects the southbridge to the disk drives.
* The AGP bus connects the video card to the memory and the CPU. The speed of the AGP bus is usually 66 MHz.
* The PCI bus connects PCI slots to the southbridge. On most systems, the speed of the PCI bus is 33 MHz. Also compatible with PCI is PCI Express, which is much faster than PCI but is still compatible with current software and operating systems. PCI Express is likely to replace both PCI and AGP busses.
The faster a computer's bus speed, the faster it will operate -- to a point. A fast bus speed cannot make up for a slow processor or chipset.
If you have been shopping for a computer, then you have heard the word "cache." Modern computers have both L1 and L2 caches, and many now also have L3 cache. You may also have gotten advice on the topic from well-meaning friends, perhaps something like "Don't buy that Celeron chip, it doesn't have any cache in it!"
It turns out that caching is an important computer-science process that appears on every computer in a variety of forms. There are memory caches, hardware and software disk caches, page caches and more. Virtual memory is even a form of caching. In this article, we will explore caching so you can understand why it is so important.
A computer is a machine in which we measure time in very small increments. When the microprocessor accesses the main memory (RAM), it does it in about 60 nanoseconds (60 billionths of a second). That's pretty fast, but it is much slower than the typical microprocessor. Microprocessors can have cycle times as short as 2 nanoseconds, so to a microprocessor 60 nanoseconds seems like an eternity.
What if we build a special memory bank in the motherboard, small but very fast (around 30 nanoseconds)? That's already two times faster than the main memory access. That's called a level 2 cache or an L2 cache. What if we build an even smaller but faster memory system directly into the microprocessor's chip? That way, this memory will be accessed at the speed of the microprocessor and not the speed of the memory bus. That's an L1 cache, which on a 233-megahertz (MHz) Pentium is 3.5 times faster than the L2 cache, which is two times faster than the access to main memory.
Some microprocessors have two levels of cache built right into the chip. In this case, the motherboard cache -- the cache that exists between the microprocessor and main system memory -- becomes level 3, or L3 cache.
There are a lot of subsystems in a computer; you can put cache between many of them to improve performance. Here's an example. We have the microprocessor (the fastest thing in the computer). Then there's the L1 cache that caches the L2 cache that caches the main memory which can be used (and is often used) as a cache for even slower peripherals like hard disks and CD-ROMs. The hard disks are also used to cache an even slower medium -- your Internet connection.
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