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This article mainly introduces what are the three types of computer buses. It is very detailed and has a certain reference value. Friends who are interested must finish reading it.

The three types of computer buses are control bus, address bus and data bus. The control bus is used to transmit the signal of the microprocessor control unit to the peripheral device, the address bus is used to specify the address of the data stored in the RAM, and the data bus is used to transfer the data to be processed or stored back and forth between the CPU and the RAM.

Bus is a common communication trunk that transmits information between various functional components of a computer. It is a transmission harness composed of wires. According to the types of information transmitted by the computer, the computer bus can be divided into data bus, address bus and control bus, which are used to transmit data, data address and control signals respectively.

Bus is a kind of internal structure, which is a common channel for cpu, memory, input and output devices to transmit information. each part of the host computer is connected by the bus, and the external equipment is connected with the bus through the corresponding interface circuit, thus forming the computer hardware system. In a computer system, the common path through which information is transmitted between various components is called a bus, and a microcomputer connects each functional component with a bus structure.

Buses can be divided into five types according to their functions and specifications:

Data bus (Data Bus): transfers data that needs to be processed or stored back and forth between CPU and RAM.

Address bus (Address Bus): used to specify the address of data stored in RAM (Random Access Memory).

Control bus (Control Bus): transmits the signal of the microprocessor control unit (Control Unit) to the peripheral device.

Extended bus (Expansion Bus): a bus for data communication between external devices and the host computer, such as ISA bus, PCI bus.

Local bus (Local Bus): an extended bus that replaces higher speed data transmission.

The data bus DB (Data Bus), the address bus AB (Address Bus) and the control bus CB (Control Bus) are also referred to as the system bus, that is, the bus in the general sense.

Bus characteristics

Because the bus is a set of signal lines connecting various components. The information is expressed by the signals on the signal line, and how to realize the operation can be agreed upon by agreeing on the order of different signals. The bus has the following characteristics

(1) physical characteristics: physical properties, also known as mechanical properties, refer to some characteristics shown by the components on the bus when they are physically connected, such as the geometric size, shape, number of pins and arrangement order of plugs and sockets.

(2) functional features: functional features refer to the functions of each signal line, such as the address bus used to represent the address code. The data bus is used to represent the transmitted data, and the control bus represents the command, state, etc., of the operation on the bus.

(3) Electrical characteristics: electrical characteristics refer to the direction of the signal on each signal line and the level range that indicates the effectiveness of the signal. Usually, the signal emitted by the main equipment (such as CPU) is called the output signal (OUT), and the signal sent to the main device is called the input signal (IN). Usually the data signal and address signal define the high level as logic 1 and the low level as logic 0, while the control signal has no common convention, such as WE for low-level efficiency and Ready for high-level efficiency. There is no uniform regulation for the high-level and low-level range of different buses, which is usually consistent with TTL.

(4) time characteristic: time characteristic, also known as logic characteristic, refers to when the signal on each signal line is valid in the process of bus operation. Through the effective timing agreement of this signal, the correct operation of the bus is ensured. In order to improve the extensibility of the computer and the versatility of components and devices, except for the on-chip bus, all components or devices are connected to the bus in a standardized form, and the information transmission on the bus is realized in a standardized way. These standardized connection forms and operation modes of the bus are collectively referred to as the bus standard. Such as ISA, PCI, USB bus standards, etc., accordingly, the buses that adopt these standards are ISA bus, PCI bus, USB bus and so on.

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