1. The function of the data path The path through which
data is transferred between functional components is called the data path. The transmission path between the arithmetic unit and each register is the internal data path of the central processing unit.
The data path describes where the information starts, which register or multiplexer passes through, and which register is finally transmitted to. These must be controlled.
The task of establishing the data path is completed by the "operation control component". The function of the data path is to realize the data interaction between the arithmetic unit and the register and the register inside the CPU.
2. The basic structure of the data path The basic structure of the
data path mainly includes the following two:
(1) Single bus mode within the CPU. The input and output ends of all registers are connected to a common path. This structure is relatively simple, but there are more conflicts in data transmission and lower performance. If there is only one bus connecting each component, it is called a single bus structure; if there are two or more buses in the CPU, it constitutes a dual bus structure or a multi-bus structure.
(2) Three-bus mode inside the CPU. Connect the input and output terminals of all registers to multiple common channels. In contrast, only one data is allowed to be transmitted in one clock in a single bus, and the instruction execution efficiency is very low. Therefore, the multi-bus method is adopted, and the Transmit different data on multiple buses to improve efficiency
(3) Dedicated data path mode. Arrange the connection lines according to the flow direction of the data and address during the execution of the instruction, and avoid using the shared bus. The performance is relatively high, but the hardware volume is large.
