Computer system Overview----PC hardware

Computer composition

Digital Computer hardware system Consists of five parts: an operator, a controller, a memory, an input device, and an output device. Each section is connected to a block diagram:

　　　


In general, the main parts are connected by bus in the computer, the block diagram is as follows:

　　　　
　　　
A large and high-speed exchange of information between parts of a computer is required to achieve overall functionality. For example:

· The CPU reads instruction and data from memory, and then stores the result in memory after operation.
· CPU and I/O device Exchange data;
· The CPU reads the status information of the device from the interface in order to understand the status of the equipment work;
· The CPU outputs commands to the interface to start and control the device work;
Wait a minute

The three sub-buses (data bus, address bus, and control bus) included in the system bus can efficiently provide high-speed,
Reliable information transmission channel.


CPU

Memory

Input
　
Bus

　　　Instance Demo button
　　　
　

Von neumann System structure

The principle of computer composition is based on the von Neumann architecture of the computer, the basic design idea is stored procedures and program control, with the following characteristics:

(1) Using binary form to represent data and instructions

In the computer where the program is stored, the data and instructions are stored in binary form in memory. There is no difference between the contents of the memory storage. is a sequence of codes consisting of 0 and 1, only the meanings of the respective conventions are different. When the computer reads the instruction, it considers the information read from the computer as an instruction, while reading the data reads the information from the computer as the operand. Data and directives have been differentiated in software development, so there is no confusion between the two under normal circumstances. Sometimes we also refer to the data and instructions stored in the memory as the data, because the program information itself can also be treated as objects, processing, such as the control program compiled, that is, the source program as a processed object.

(2) Using the stored procedure method

This is the core content of von Neumann thought. As mentioned above, it means that the program is programmed beforehand, the program (including instructions and data) is stored in the main memory, and the computer can automatically and continuously remove the instruction from the memory and execute it sequentially when the program is run. This is the basis for the computer to run at high speed. The work of the computer manifests as the execution program, the extension of the computer function is also reflected to the extension of the stored program to a great extent. Many of the specific ways computers work are also derived from this.
This mode of operation of the von Neumann machine can be called the control flow (instruction flow) drive mode. That is, according to the instruction execution sequence, read the instruction sequentially, and then according to the control information contained in the instruction, call the data for processing. Therefore, in the process of executing the program, always to control the flow of information as a driving factor, and the data flow is passively called to deal with. To control the order in which the sequence of instructions is executed, set up a program (instruction) counter PC (Counter) to hold the address of the storage unit where the current instruction is located. If the program is now executed sequentially, the PC content plus L after each instruction is taken, indicating where the next instruction is to be obtained. If the program is moved somewhere, the transferred destination address is fed to the PC so that subsequent instructions are read at the new address. So, a PC is like a pointer, which always indicates the process of executing the program, which indicates the formation of the control flow. Although the program and data are binary code, you can still follow the contents of the PC as the address read instruction, and then follow the instructions given by the operand address to read the data. Because most of the time the program is executed sequentially, most of the instructions need to be placed next to each other, except that the individual data to be used can be stored next to the instruction, and the instructions and data are stored in different areas of the program area.

(3) The computer system is composed of five parts of the arithmetic device, memory, controller, input device and output device, and the basic function of the five part is stipulated.

These concepts have laid the basic structure of modern computers, so far, the majority of computers still use this system, that is, the von Neumann computer system.

Non-Neumann

It must be seen that the traditional von Neumann-type computer is essentially a sequential processing mechanism, and even if the data is prepared, the sequence of instructions must be executed on an article by article. And one of the fundamental directions of improving computer performance is parallel processing. Therefore, in recent years people seek to break through the shackles of traditional von Neumann system, this kind of effort is called non-Neumann. The discussion of the so-called non-Neumann is still in dispute, and it is generally considered as a manifestation of the following three efforts.

(1) in the scope of the von Neumann system, the traditional Feng Neumann is reformed, such as the use of multiple processing parts to form a water treatment,
Relying on the overlapping of time to improve the processing efficiency, and the formation of the structure of the array, to form a single instruction flow multi-data flow, improve processing speed
Degree. These directions have matured to become standard structures;

(2) using multiple Feng Neumann to compose multi-machine system, support parallel algorithm structure. The research in this area is more active now;

(3) Fundamentally change the control flow drive mode of von Neumann machine. For example, data flow calculations that use data flow-driven working methods
The instructions can be executed in parallel as long as the data is ready. This is a truly non-Neumann computer, and it
New prospects, but because of the complexity of control, is still in the experimental exploration.

One, 1. B
　　
2. D
　　
3. A

Two, 1. Program Address von Neumann
　　
2. instruction Flow Data Flow
　　
3. System Program Application

　

From: http://cs.xiyou.edu.cn:84/jsjzcyl/a/zjs031020.htm#

Computer system Overview----PC hardware