In order to ensure that the local defense forces and overseas defense forces still have a certain ability to survive and counterattack after the first H strike, the Ministry of Defense of a certain country believes that it is necessary to design a decentralized command system.

It consists of scattered command points, and when some of them are destroyed, others are still functional, and they can continue to communicate with each other, bypassing those that have been destroyed.

The country's Ministry of Defence strongly supported research on networking, which began online in December 1969.

The aim is to re-establish the country's leadership in the development of JS technology applications. At that time, the network transmission capacity was only 50Kbps, which was very low by standards.

Initially, 15 nodes were connected with a total of 23 hosts.

By 1972, there were 40 outlets, which could send small text files to each other. At that time, this type of file was called e-mail, which is what we now call e-mail.

With the use of the network and in-depth research, in 1973, the TCP/IP protocol appeared.

Li Guocheng didn't expect that his unintentional move would also attract the attention of the Huaxia military, and the starting point was so similar.

After pondering for a while, Li Guocheng was ready to adopt a transitional plan, first to accumulate application experience, and then to allow time for the development of the TCP/IP protocol.

Of course, the idea can be borrowed, but the name must no longer be called TCP/IP protocol.

The word "Kyushu interconnection" rushed into Li Guocheng's mind, Kyushu was the name of China in ancient times, and it can also refer to the major states of the world.

Thinking of this, Li Guocheng said: "I have a transition plan here, the communication protocol is relatively simple, the rate can reach 500Kbps, and there is no problem with the distance of 1 km.

The final solution communication protocol is relatively complex, and the communication rate should reach 10Mbps. But now it's just an idea, it takes time to study, and the specific delivery time is uncertain.

The advantage of using a transition scheme is that you can accumulate experience and find problems in communication, and we can modify them together until we finally meet the actual use. And then all the experience was transplanted directly into the final solution."

Li Guocheng finished his train of thought in one breath and waited for their conclusion.

The three of them lowered their heads and discussed for a while, and Ma Jianmin asked, "Is 1 kilometer the farthest communication distance?" Is there a way to extend? ”

"Oh, I didn't make it clear, I was referring to a small LAN with a maximum of 1 kilometer, and if it goes through a repeater, this distance can still be extended a lot. Theoretically, it can be infinitely long", replied Li Guocheng.

The servants glanced at each other, their eyes full of joy, and they bowed their heads and discussed for a while.

"That's great! We choose the transition option. But there is a suggestion that the embedded cable must be considered to reserve the cable of the final solution," Ma Jianmin said.

Li Guocheng just pondered for a while, "You can consider designing a universal cable, and then you only need to replace the relay, and the cable does not need to be moved."

"That's better, it's decided, go to the transition plan first", Ma Jianmin said happily, without asking the other two for their opinions. Li Guocheng understands that Ma Jianmin is the leader.

Set up a plan for 1 month, and deliver samples for them to test in half a year.

After the three of them left, Li Guocheng said to Li Huaide: "The director of this system is too huge, there are only three people in our software group, it will definitely not be completed, you have to find a way."

"How many people do you need?"

"At least 5 people, the more the merrier," Li Guocheng said with a smile.

"You little monkey, up to 5 people, is there more", Li Huaide saw Li Guocheng's intentions.

Li Guocheng deliberately pretended to be heartbroken, but in fact, his heart was already happy. His minimum expectation is 2 people, and he deliberately said this because he gave Li Huaide a handle to handle him in the future.

Li Guocheng, who returned to the laboratory, called Yan Jiefang and Zhang Zhijing to the office and helped them make tea.

"Now there is a mission, it is more urgent, and we all have to suspend the task at hand."

"What kind of mission? It's so urgent," Zhang Zhijing asked.

"We need to develop a communications network for the military, similar to the 485, but at a much faster and longer distance than the 485 bus."

Next, Li Guocheng explained to them the knowledge of the Internet, which has brought changes to the national economy and people's livelihood. After listening to this, the two felt that they had entered a new realm, and they were eager to realize the Internet described by Li Guocheng.

Kyushu Internet defines a four-layer architecture, from low to high: physical layer, link layer, network layer and application layer, and Li Guocheng instills network knowledge in them according to his own understanding.

He is not afraid of misunderstanding mistakes at all, because as long as he grasps the correct direction, everything else can be corrected, because everyone is groping now.

In terms of communication theory, he stood directly on the shoulders of giants, and his university education gave him a general understanding of the basic theory of communication, and his one-year practice in the computer room gave him a framework for his understanding of the network.

The only thing that makes him difficult to grasp is the speed of the current chip, which restricts his play, but officially based on the development of the first generation of chips, he can start from the basics, but the network communication will be more basic and deep.

After a single explanation, the two of them had a basic understanding of the Internet.

"Xiao Zhang, you focus on how to build the network layer. Liberation, you are first familiar with the hardware structure of Kyushu Internet V1.0, focusing on contacting the cable factory.

If they don't know how to produce a characteristic impedance cable, you tell them the cable parameters and then tell them how to test the impedance. If you can't do it, you can also provide them with a set of electric bridges, and remember to charge a fee."

After the two left, Li Guocheng put away the sketch he had sketched just now and began to build the network chip in his mind.

Considering the actual situation of the country, the 103 motherboard does not want to make a big move for the time being, and tries to make partial modifications to meet the actual use, so that you can have the money left to upgrade the host.

The 485 chip is connected to the CPU with a parallel bus, and the external is a serial differential bus, with a characteristic impedance of 150 ohms. A total of two 485 channels are reserved on the motherboard.

Just PINtoPIN can be replaced, the 485 chip reserves pins to connect a 12V voltage on the motherboard, and you can output a differential output ± 12V, which can transmit a longer distance.

The new chip can refer to the CAN2.0 protocol in the future, but it needs to be modified, the frame head, frame end, and arbitration can be retained, but the data cannot be 8 bytes, and the maximum can be 128 bytes.

In this way, the voltage can be adjusted up, which can resist long-distance voltage attenuation, and the data frame becomes longer, ensuring the effective rate.

The data rate is tentatively set at 500Kbps, which is better than their 50Kbps.

Lee's greatest confidence is that the world only realized signal integrity and electromagnetic interference in the 80s, but we have already considered it in our current design.

The external interface chips are built with built-in electrostatic protection circuits, and the circuit board design has considered signal integrity and impedance matching, and EMC has been considered in the design of the whole machine.

Thank you all for your support!! Ask for recommendations! Ask for a commuter pass! Ask for a review!

(End of chapter)