Front-side bus frequency

A bus is a set of transmission lines that transfer information as one or more source components to one or more destination components. In layman's terms, there is a common connection between multiple components used to transfer information between components. People often describe the bus frequency at the speed expressed in MHz. There are many types of buses. The English name of the front-side bus is the Front Side Bus, which is usually represented by FSB. It is the bus that connects the CPU to the North Bridge. The front-side bus frequency of the computer is determined by both the CPU and the North Bridge.

The Northbridge chip is responsible for contacting the components with the highest data throughput, such as memory and graphics cards, and is connected to the Southbridge chip. The CPU is connected to the North Bridge chip through the front-side bus (FSB), and then through the North Bridge chip and memory, graphics exchange data. The front-side bus is the most important channel for exchanging data between the CPU and the outside world. Therefore, the data transmission capability of the front-side bus has great effects on the overall performance of the computer. If the front-side bus is not fast enough, then a strong CPU cannot significantly improve the overall speed of the computer. The maximum bandwidth for data transmission depends on the width and transmission frequency of all simultaneously transmitted data, ie, data bandwidth = (bus frequency × data width) ÷8. At present, the front-side bus frequency that can be reached on the PC has several kinds of 266MHz, 333MHz, 400MHz, 533MHz, 800MHz, up to 1066MHz. The larger the front-side bus frequency, the greater the data transfer capability between the CPU and the Northbridge, and can fully utilize the functions of the CPU. The current CPU technology has developed rapidly and the computing speed has increased rapidly. A sufficiently large front-side bus can guarantee enough data to be supplied to the CPU. The lower front-side bus will not be able to supply enough data to the CPU, thus limiting the CPU performance. Have to play, become a bottleneck in the system.

The difference between the FSB and the front-side bus frequency: The speed of the front-side bus refers to the speed of the bus between the CPU and the North Bridge chip, and more substantively represents the speed of data transfer between the CPU and the outside world. The concept of FSB is based on the pulsation speed of digital pulse signals. That is, the 100 MHz FSB specifically refers to the digital pulse signal oscillating at 1 million times per second. It has more impact on PCI and other buses. Frequency of. The reason why the two concepts of FSB and FSB are confusing, the main reason is that in the previous long time (mainly before the appearance of the Pentium 4 and when the Pentium 4 appeared), the FSB frequency is the same as the FSB. Therefore, the front-side bus is often referred to directly as the FSB, eventually causing such misunderstandings. With the development of computer technology, people have found that the front-side bus frequency needs to be higher than the FSB, so QDR (Quad Date Rate) technology or other similar technologies are used to achieve this goal. The principle of these technologies is similar to AGP 2X or 4X, which makes the frequency of front-side bus become 2 times, 4 times or even higher than FSB. Since then, the difference between front-side bus and FSB has begun to be paid attention to by people. The products use these technologies.