In the von Neumann computer model, memory refers to the "memory" unit; in the von Neumann computer model, the stored program method is used, and instructions and data are mixed and stored in the same memory without distinction, and data and There is no difference between programs in memory, they are all data in memory.
#The operating environment of this article: Windows 7 system, Dell G3 computer.
The Hungarian-American mathematician von Neumann proposed the stored program principle in 1946, treating the program itself as data, and the program and the data processed by the program are stored in the same way. Von Neumann architecture The key points of von Neumann theory are: the computer's number system uses binary; the computer should execute in program order. People call this theory of von Neumann the von Neumann architecture.
Characteristics of the von Neumann computer model
1. The data and instructions processed by the computer are all represented by binary numbers
2. Sequential execution of programs
When the computer is running, the program to be executed and the data to be processed are first stored in the main memory (memory). When the computer executes the program, it will automatically fetch the instructions from the main memory and execute them one by one in order. This concept is called Execute programs sequentially.
3. Computer hardware consists of five major parts: arithmetic unit, controller, memory, input device and output device.
Operator: As the name suggests, it mainly performs calculations, arithmetic operations, logical operations, etc. are all completed by it.
Memory: The memory here is just memory, not including external memory, used to store data and instruction information.
Controller: The controller is the dispatching center of all equipment, and it is responsible for the normal operation of the system.
Input device: Responsible for inputting data into the computer, such as mouse, keyboard, etc.
Output device: Responsible for outputting data after the execution of computer instructions, such as monitors, printers, etc.
Model structure
(1) Using stored program method, instructions and data are mixed and stored in the same memory without distinction, and data and There is no difference between programs in memory. They are all data in memory; when the EIP pointer points to where it is, the CPU loads the data in that memory. If it is an incorrect instruction format, the CPU will cause an error interrupt. In the current protected mode of the CPU, each memory segment has its descriptor, which records the access rights (readable, writable, and executable) of this memory segment. This specifies in disguise which memories store instructions and which data)
Both instructions and data can be sent to the arithmetic unit for calculation, that is, the program composed of instructions can be modified.
(2) The memory is a linearly addressed one-dimensional structure accessed by address, and the number of bits in each unit is fixed.
(3) The instruction consists of operation code and address code. The opcode specifies the operation type of this instruction, and the address code specifies the operand and address. The operand itself has no data type flag, and its data type is determined by the opcode.
(4) Directly send control signals to control the operation of the computer by executing instructions. Instructions are stored in the memory in order of execution, and the instruction counter indicates the unit address of the instruction to be executed. There is only one instruction counter, which generally increases sequentially, but the execution order can be changed according to the operation results or the external conditions at the time.
(5) With the arithmetic unit as the center, data transmission between I/O devices and memory must pass through the arithmetic unit.
(6)Data is expressed in binary
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