Bus (Bus) is a public communication lines to transfer information between various functional components of the computer, which is composed of a transmission by a wire harness. According to the kind of transmitted information the computer, computer bus can be divided into a data bus, an address bus and a control bus, are used to transmit data, address and control signals. Bus is an internal structure that is cpu, memory, input and output device common information transmission channel, the respective components are connected by the host bus, then the external device connected to the bus via a respective interface circuit, thereby forming a computer hardware system. In a computer system, the common channel to transfer information between the various components is called a bus, a microcomputer is connected to the bus structure of the various functional components. We usually say that the CPU bus, refer to the external bus.
- Data Bus
The data bus is the CPU and the memory, transferring data between the CPU and I / O interface device information (various instruction data) to the bus, these signals via the data bus to and from the CPU and the memory, CPU and I / O interface equipment room, therefore, information on the data bus is two-way transmission. - An address bus
transmitting the address information on bus address is sent to the CPU memory, I / O interface device, address information transmitted on address bus is made by the CPU, and therefore, the information on the address bus is unidirectional transmission, by CPU to specify the address bus of the memory cell, which determines the size and scope of the addressing capability of the CPU to access memory - A control bus
to control the bus transfer various control signals, to achieve an external device controlled by a memory control signal to the CPU, I / O interface device, there are I / O interface response signal is sent to the CPU, the request signal, and therefore, the control bus is a bidirectional transmission of information on. The control signal includes a timing signal, status and command signals (such as read and write signals, a busy signal, an interrupt signal) and the like. - In fact, there is a bus, internal CPU, to arithmetic unit / data bus registers each pass is called internal data bus, the CPU determines that the word length.