Von noriman structure and Harvard Structure

Feng nuoman Structure
Feng. noiman first proposed the concept of "Storage program" and the binary principle. Later, people referred to the electronic computer system designed using this concept and principle as "Feng. noniman-type structure "computer. The processor of the Von noriman structure uses the same memory and transmits data through the same bus.

The von noriman structure processor has the following features:

There must be a memory;

There must be a controller;

There must be an iterator for completing arithmetic and logical operations;

There must be input and output devices for human-computer communication.

Feng nuoman's main contribution is to propose and implement the concept of "storage Program. Since commands and data are both binary codes, and the address of commands and operands are closely related, it is natural to select this structure. However, this command and data share the same bus structure, making the transfer of information flow a bottleneck restricting computer performance, affecting the speed of data processing.
In typical cases, it takes three steps to complete an instruction, namely, obtaining the instruction, decoding the instruction, and executing the instruction. From the regular relationship of the instruction flow, we can also see the difference between the structure of von noiman and that of the Harvard structure. For example, the simplest command to perform read/write operations on the memory, as shown in, commands 1 to 3 are memory and fetch commands. the nuoman structure processor, because the command and data access need to be accessed from the same bucket and transmitted through the same bus, they cannot be overlapped for execution, and only one is complete before the next step.

 

 

Harvard Structure
Digital Signal Processing generally requires a large amount of computing and a high computing speed. To improve data throughput, most of the digital signal processors use the Harvard structure,

 

Figure Harvard Structure
Compared with von noriman's structure processor, Harvard's structure processor has two notable features:

Two independent storage modules are used to store commands and data respectively. commands and data cannot coexist in each storage module;

The two independent bus are used as the dedicated communication path between the CPU and each memory, and there is no association between the two bus.

Later, an improved Harvard structure was proposed.

 

Its structure features:

Two independent memory modules are used to store commands and data respectively. Each storage module does not allow the coexistence of commands and data for parallel processing;

With an independent address bus and an independent data bus, the public address bus is used to access two storage modules (program storage module and data storage module ), the Public Data Bus is used to transmit data between the program storage module or data storage module and the CPU;

The two buses are shared by the program memory and data storage at time.

In typical cases, it takes three steps to complete an instruction, namely, obtaining the instruction, decoding the instruction, and executing the instruction. From the regular relationship of the instruction flow, we can also see the difference between the structure of von noiman and that of the Harvard structure. For example, the simplest command to perform read/write operations on the memory, as shown in, commands 1 to 3 are memory and fetch commands. the nuoman structure processor, because the command and data access need to be accessed from the same bucket and transmitted through the same bus, they cannot be overlapped for execution, and only one is complete before the next step.

 

 

If the Harvard structure is used to process the preceding three access data commands, as shown in, since the commands and access data go through different buckets and different bus, this allows the execution of each command to overlap, which overcomes the bottleneck of data stream transmission and improves the computing speed.
The Harvard structure emphasizes the overall system speed and flexibility in communication and processor configuration.

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In general, the high performance of Harvard organizations is embodied in a small number of program types and patterns running on single chip microcomputer and DSP chip platforms, because there are few software upgrades in various electronic entertainment products, applications can use assembly as the kernel to achieve the highest efficiency by using the pipeline technology with the highest efficiency.

The von noiman structure is mainly based on the different ways that computer buyers use computers-various entertainment users, various professional development users, and a wide variety of installed software, with frequent upgrades, the priority of processing when multiple types of software are running at the same time is relatively vague. Intel chip does not have a mechanism for completely intelligent allocation of the priority of each program and the pipeline. The mechanical allocation priority and pipeline are easy to cause inconvenience to users.