Rebirth of the Tech Madman

It can be said that this dual-world situation is a reflection of the differences between theory and practice, academic and business, and the realization of the principle of LAN technology.

Logically, Ethernet adopts a bus-type topology and uses csma/cd, the bus contention technology of carrier sense multiple access/collision detection.

Between each node on the network, that is, between computers, from sending to receiving, there will be a transmission unit, that is, the concept of data packet-frame.

-Cs, or carrier sense, means that any computer connected to the network must listen to the network before sending a frame, and can only send it when it is confirmed that it is idle.

-Ma means multiple access means that multiple computers can access the network at the same time, and frames sent by one computer can also be received by multiple computers, which is similar to broadcasting.

Obviously, this kind of network usage will inevitably cause frame collisions.

Just like a two-way two-lane road, the "frames" of motorized vehicles, non-motorized vehicles, people, pets, etc. are all vying to get on the road, and accidents such as scratching will inevitably occur.

The collision problem cannot be cured, but it can be alleviated through some listening/sending strategies. One of the solutions is-cd stands for collision detection.

It requires the computer to listen to the network while sending frames to determine whether a collision occurs.

If a collision is detected in the process of sending data. Then carry out the following collision handling operations:

first of all. Send special blocking information. And immediately stop sending data. The special blocking information is an all-one signal of several consecutive bytes. This is intended to strengthen the collision so that other computers can detect the collision as soon as possible.

The image point is to break the can, so that everyone can see the heavy traffic, so don't go on the road.

Second, wait for a random time within a fixed time and send again.

At last. If the collision still occurs, the "truncated binary exponential avoidance algorithm" is used to send. That is, within ten times, stop sending at random within twice the time of the previous “fixed time”, and after ten times, stop sending at random within the previous “fixed time”. After 16 attempts, the transmission still fails.

This method is like in a metropolis with heavy traffic, the relevant departments arrange odd and even number restrictions according to the license plate number.

Obviously, collisions in the operation of Ethernet will cause a certain degree of waste of resources and lack advantages in execution efficiency.

In sharp contrast to this. A 4m token ring network is equivalent to a 10m Ethernet data transfer rate. The data transfer rate of a 16m token ring network is close to a 100m Ethernet.

The reason why there is such an obvious gap is of course because the basic operating principles of each other are completely different.

The token ring network uses tokens that represent signalling permissions to avoid conflicts in the network.

The computer that gets the token is like the exclusive lane of a police car pulling an alarm. It exclusively sends data through the network. Compared with the operation mechanism of computers on the Ethernet that constantly probes and finds blocking opportunities, it naturally increases the data transmission rate of the network.

Moreover, the transmission priority can also be set through the token to meet high-level network resource requirements.

In theory, the token ring network is impeccable, but in practice, the utilization rate of the token ring network is low because the network cannot be reused.

When a computer in the network gets the token and starts to use the network, no matter how much bandwidth the computer uses, even if it only uses 1m of the 4m, other computers must wait for it to use the network and give up the token before they have a chance. Apply for a token and use the network.

It's like driving a privileged car on a road without interruption. Even if there are eight lanes, other ordinary vehicles can only stare and cannot get on the road.

Especially when the network becomes complicated, the programs running in each computer are written by humans, and the implicit desire to monopolize the network makes the theoretical circulation of the tokens smooth, unable to get the expected guarantee. Correspondingly, The utilization of network resources is not high.

Generally speaking, the token ring network similar to the planned economy is not as vigorous as the Ethernet similar to the market economy.

The benefits of spontaneously coordinated use of the network between computers on the Ethernet exceed the loss caused by the collision phenomenon.

However, the correct understanding of this point is far from widespread. Theorists and large companies such as ibm are favoring token ring networks.

The well-known computer scientist jerrysaltzer pointed out in an influential paper co-authored with others that, theoretically, token ring networks are superior to Ethernet.

Before Ken Thompson and Dennis Ritchie developed the C language based on the C language, in 1964, Bell Labs, Massachusetts Institute of Technology and General Electric Co., Ltd. jointly participated in the research and development of a set of installations on the mainframe. Multi-tasking operating system-that is, jerrysaltzer was one of the leaders of the team at that time.

Therefore, jerrysaltzer's status is not low. His views are very influential. Affected by this conclusion, many computer manufacturers either hesitate or simply decide not to use the Ethernet interface as the standard configuration of the machine.

However, the advantages of the simple structure of Ethernet in the actual use process cannot be ignored. In the original time and space, it was a blessing in disguise that was left out in the cold. By selling a separate Ethernet network card, it made a big profit, and it quickly grew into an international company. An almost joking statement-"Ethernet is not suitable for research in theory, but only suitable for application in practice."

However, the brilliance of 3 will have to wait a few years, and now this company has been established for more than a year. Lobbying other vendors everywhere. Accept your own technology.

so far. Robert Metcalf, who is running around, has also made some progress, such as cooperating with Intel, Xerox, and standardizing Ethernet, launching a standard, and developing a commercial version for use.

And Tang Huan's goal is to take out a personal computer version with 3 and occupy the highest point in the industry.

Because of Simeone's relationship. Tang Huan had already had some contact with Robert Metcalf earlier, so various verbal temptations during the meeting can be omitted directly.

Accompanied here were another man and a woman, two philosophical engineers in their 30s: David Boggs and Radia Perlman.

Since the popularity of the database ebase in the market at the end of last year, especially after the sales of Xiaobawang game consoles exploded, the company under Tang Huan's name has become more attractive to high-end talents, and there is basically no need for his boss to spend any thought People.

In the original time and space, David Boggs and Radia Perlman both went this year. As a result, the human resources department of Zheru, who was ordered to recruit network talents for the 386 plan, recruited the company. This kind of search ability made Tang Huandu amazed.

usually. People think that Ethernet was invented in 1973, because Robert Metcalfe wrote a memo about the potential of Ethernet to his boss.

However, Robert Metcalf himself believes that Ethernet only appeared in the next few years. That is, in 1976, Robert Metcalfe and his assistant David Boggs jointly published an article titled "Ethernet: Distributed Packet Switching Technology for Regional Computer Networks".

Robert Metcalfe left and went to found 3. David Boggs also left, but he got a master's degree and stayed on the West Coast, planning to study for a PhD at Stanford University, and then came to Philosopher.

As for Radia Perlman, after graduating from the Massachusetts Institute of Technology with a master's degree in mathematics, she was engaged in the software development of network equipment. I don't know how Zheru's human resources department fooled and took her from the east coast to the west coast.

Don't underestimate this point. American universities are divided into circles. What kind of university a person chooses often means his future job level and even the scope of his spouse selection.

In the original time and space, Radia Perlman made a lot of technical achievements. The most important point may be 1983. She invented the spanning tree algorithm and developed the stp spanning tree protocol for bridges and switch equipment. , Is of great significance to the establishment of large-scale networks.

Later, Radia Perlman was dubbed the "Mother of the Internet", but it is said that she did not like this title.

Radia Perlman’s work is actually to develop a basic data transmission method for the network (inter).

It is no exaggeration to say that the technicians on site are all network experts.

However, Tang Huan did not want to enter the technical discussion immediately. He first asked about the possibility of investing in 3, because Robert Metcalf attracted a lot of venture capital when he founded the company, so he didn't have the right to speak. Now, there are some things that he can't call the shots.

One of the manifestations is that the three recent board of directors have invited another one. As for Robert Metcalf, he was appointed as the chairman of the company's board of directors and concurrently served as the company's vice president of marketing and sales, which is a balanced power structure.

In Tang Huan's view, such operations by capitalists have their own reasons. Entrepreneurs with professional and technical backgrounds may not be able to manage their own companies.

In the original time and space, Robert Metcalf was finally swept out in 1990, similar to the two founders of Cisco, the time is not far apart, and the two companies have also entered a period of rapid growth after a short period of adjustment. .

It's useless to complain too much. Even if the truth is so cruel, the creators need introspection, at least Tang Huan thinks so.

Moreover, Robert Metcalf is very active and plays the role of a prophet in the Internet world.

He once proposed the famous Metcalfe's Law, which is comparable to Moore's Law: "The value of the network is proportional to the square of the number of connected users."

Various social software have verified the correctness of this statement, a big v account with thousands of fans on Weibo. What is its value. It's obvious to all.

Of course. Robert Metcalf's big mouth is not always correct, and it provokes ridicule on himself.

For example, Robert Metcalf once predicted in 1995 that the Internet would usher in a devastating paralysis in 1996. In fact, of course, everyone is fine.

Robert Metcalf also predicted that wireless networks would die out in the mid-1990s, but the reality is that users are looking for signals everywhere.

Robert Metcalf did not stop there, and made the "social network bubble" remarks. It seems that related companies are still making a lot of money.

It can be seen that the so-called forerunners, the mythological aura is forced by others, at least when Tang Huan was dealing with Robert Metcalf, he felt that the other party was normal.

For example, he can see that Robert Metcalfe is happy to see himself investing in 3, because Robert Metcalfe hopes to have an additional partner on the company's board of directors.

Despite this, Robert Metcalf, who has no right to make a decision, looked embarrassed, "Don't look at me with the title of chairman of the board of directors. But I was played by those guys and discussed twice. But it was nothing. ."

"The situation is different now. We have officially launched the second-generation Fangyuan computer, which can be regarded as the first 16-bit personal computer with practical value. This brand's support for Ethernet technology is not enough to allow those people Are you interested?"

"Even so, the board of directors will not agree to sell 20% of the shares, otherwise, the existing power structure will change." Robert Metcalf spread his hands helplessly, "I suggest you lower it. Target, and use the sales performance of the more powerful second-generation Fangyuan computer as evidence of persuasion."

Tang Huan rubbed his eyebrows, and had to accept the second place.

The hard disk is a mechanical product, no matter how large its capacity or speed becomes, it cannot escape its position at the end of the industrial chain.

The Internet is different. The smartness of those venture capitals is world-class, so naturally they have long thought about it, and they are not willing to give up possible future benefits in the early stage of development.

Seeing Tang Huan’s good faith, Robert Metcalfe heaved a sigh of relief and joked, “You’d better make a formal trip to 3 and let the members of the board of directors see you, who has made billions in the personal computer industry. The wealthy man has shocked some of these guys."

It seems that Robert Metcalf, who is a little angry, hopes to support him.

Tang Huan smiled and nodded, "Let’s not mention this for now. Let’s talk about the realization of Ethernet on the second-generation Fangyuan computer. Zheru mainly does software work, your network card, and drivers, the sooner you get it. Come out, the more the industry will know the advantages of Ethernet."

"To be honest, the degree of philosopher's enthusiasm for LAN is beyond my expectation. Can you tell me what heavyweight applications you have?" Robert Metcalf asked tentatively.

Tang Huan glanced at Simeone with admiration, regardless of the fact that the other party had a friendship with Robert Metcalf, but he was unambiguous in keeping business secrets.

"We are developing a major functional upgrade of the database ebase, which is to support the client-server structure." Tang Huanliang gave Zheru's dry goods a bit.

"Can I take a look at the demo?" Robert Metcalf, who was bright in front of him, suddenly became very interested.

The structure-the c/s structure is also called-the master-slave architecture. The characteristics of this technology can be seen only from the literal meaning.

The c/s structure is not a new thing, it has been studied as early as the 1970s, so Robert Metcalfe is no stranger.

"Of course, we have already built a simulation platform." Tang Huan asked Simeone to prepare for the presentation, and he continued to discuss the Ethernet cooperation with Robert Metcalf.

After taking a look at David Boggs and Radia Perlman, Robert Metcalfe said with emotion, "Tang, you have a long-term vision in terms of technology, and the time when 3 was established It's only a few months later than Philosopher, but the layout is much worse."

"What you see is only the surface. I'm walking on thin ice now." Tang Huan shook his head and loosened his tie. "When the ibm personal computer is launched, I don't know how many companies and brands will be eliminated."

"Don't worry, 3 is basically impossible to enter the ibm camp. We are friends in the trenches." Robert Metcalf laughed.

...

After the successful research and development of Fangyuan's second-generation computer ~www.readwn.com~, the work pressure brought by it was not ordinary. Tang Huan wanted to go to Xiangjiang to relax, but couldn't spare any time.

The executives under him were equally busy. For example, Hawkins, who had just inspected the game business in Japan, had just returned to the United States and brought a message from the United States to report to Tang Huan.

It’s not long before Michael Cimino, who won the Oscar for Best Picture and Best Director honors, directed the $40 million epic western film "Heaven’s Gate", which was released on November 19.

Up to now, the audience has complained and the box office has been dismal, and it is estimated that only about 1.5 million will be recovered.

From top to bottom, Lianmei, whose family has been defeated, is panicking.

Even those who have made it clear that they will be loyal to ea in the future are beginning to feel anxious. Such a money-losing goods will not scare ea away, right? (To be continued...)

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