What is a computer bus, the difference between a bus and an interface

What is a computer bus
This is related to the structure of the computer host. First of all, we all know that the computer’s cpu is composed of two parts, one is the control unit, and the other is the arithmetic logic unit. The cpu control unit is responsible for the coordination and communication of the various components of the computer. What is communication? It is data transmission. For example, the input device transmits information to the main memory, the main memory transmits data to the cpu, and the cpu calculation result is output to the output device, and so on. The arithmetic logic of the cpu is mainly for logical operations, judgments, etc., such as addition, subtraction, multiplication, and division operations. The cpu is only responsible for computing and coordinating and controlling various components, so where does the data it needs come from? The answer is from the main memory. The input device transfers the data entered by the user to the main memory, and then the main memory transfers the data to the cpu. Then who is the transfer through? It is through the bus of the motherboard. The bus is used for data transmission. Generally speaking, the computer needs to control and coordinate various components through the motherboard. If the cpu is the brain, then the motherboard is like the nervous system. ^_^), an important component of the motherboard is a chipset, this chipset is the north bridge and the south bridge, the north bridge of the motherboard is responsible for the communication between the main memory (RAM), the display adapter (that is, the graphics card) and the cpu, the main memory To transmit data to the cpu, you need to pass through the north bridge, and then connect the bus to the cpu through the north bridge, and transmit the data to the cpu (this is the architecture of Intel, AMD directly connects the main memory and the cpu without passing through the north bridge), the north bridge The bus leading to the cpu needs to be connected to the main memory and display adapter, so it needs extremely high speed. We call this bus the system bus. The data that the bus can transmit is generally 32bit and 64bit, and these connections The equipment connecting the north bridge to the cpu has another standard to measure the transmission capacity, called the external frequency. For example, if the external frequency is 333MHz, it means that the equipment connected to the north bridge performs 3.33*10^6 per second. For second transmission, there is also a fixed multiplier in the computer. The main frequency of the cpu (and how many times per second) = FSB * multiplier. It is said that this concept is designed to coordinate high-speed cpu and low-speed external equipment = =. The amount of data transferred per second of the external device = how many times per second * bus width can be obtained.

Let’s talk about the South Bridge. The South Bridge, like the North Bridge, is also used to connect to computer devices, mainly to connect low-speed network cards, USB devices, audio, hard disks and other devices. Connecting these devices is also implicated by a bus, we call it I/ O bus, as for PCI, what is PCI-Express? Let’s talk about PCI-Express. PCI-Express is the bus interface. From the perspective of the motherboard, it is the main memory and the slot for the display adapter. PCI-Express is a new generation of bus interface that replaces the old PCI. , AGP, etc. Don’t underestimate this stuff. It affects the data transmission speed. Nowadays, many hardwares are developed to match PCI-Express. What is SATA? Like the IDE slot, it is used to connect the hard disk device, attach a picture:

What is a computer bus, the difference between a bus and an interface

The difference between bus and interface
The connection and data exchange between the CPU and peripheral devices and memories need to be implemented through interface devices. The former is called an I/O interface, and the latter is called a memory interface. The memory usually works under the synchronous control of the CPU, and the interface circuit is simple, and the quality of I/O devices is various, and the corresponding circuit interfaces are also different. Therefore, the interface used to refer to the I/O interface. For example: serial port, parallel port, USB, etc.

The bus is a collection of various signal lines, and is a common channel for transmitting data, address, and control information between various components of the computer. The parameters of the bus include: the bandwidth of the bus, the bit width of the bus, and the working clock frequency of the bus. For example: ISA, PCI, I2C, etc.

The bus is a set of transmission channels, such as the PCI bus. The interface is a connection standard, such as the PCI interface.

The relationship between the two is that PCI interface devices must communicate through the PCI bus, and the devices on the PCI bus are not all PCI.