lec6- A Data and a Control Sections

A Data and a Control Sections
CPU sections
7. DATAPATH
The CPU can be divided into a data section and a control section. The data section, which is also called the datapath, contains the registers and the ALU. The datapath is capable of performing certain operations on data items. The control section is basically the control unit, which issues control signals to the datapath. Internal to the CPU, data move from one register to another and between ALU and registers. Internal data movements are performed via local buses, which may carry data, instructions, and addresses. Externally, data move from registers to memory and I/O devices, often by means of a system bus. Internal data movement among registers and between the ALU and registers may be carried out using different organizations including one-bus, two-bus, or three-bus organizations. Dedicated datapaths may also be used between components that transfer data between themselves more frequently. For example, the contents of the PC are transferred to the MAR to fetch a new instruction at the beginning of each instruction cycle.