18.104.22.168 explain three operations in fetch-execute cycle (fetch /decode /execute)
The processor responds to and processes the instructions that drive the computer. It contains the control unit, the arithmetic/logic unit (ALU) and registers.
The control unit coordinates and controls all the operations carried out by the computer. It operates by repeating three operations:
Fetch - In this step the CPU fetches some data and instructions from main memory (RAM) and then store them in its own temporary memory called 'registers';
Decode - The decode step is where the CPU understands / works out what the instruction it has just fetched actually means.
Execute - The Execute stage is where data processing happens. Instructions are carried out on the data.
When once a cycle has completed, a new cycle begins.
Watch video to 5:15
Author: Tom Scott
The circuits used in the CPU during the cycle are:
Control Unit (CU) - decodes the program instruction in the CIR, selecting machine resources such as a data source register and a particular arithmetic operation, and coordinates activation of those resources.
Arithmetic logic unit (ALU) - performs mathematical and logical operations.
Register notation of the Fetch-Decode-Execute cycle
MAR <== [PC]
MBR <== [Memory]MARaddress; PC <== [PC]+1
CIR <== [MBR]
|Просмотров: 122 | ||
|Всего комментариев: 0|