Video Game Empire

"According to Moore's Law, the number of transistors and resistors integrated on a chip will double every two years, and the performance of CPU (central processing unit) and DRAM (main memory) is improving rapidly. But at the same time as the increase in DRAM storage capacity, However, the reading speed cannot be improved synchronously, resulting in an extremely mismatched situation with the main frequency of the CPU, which is bound to greatly affect the overall performance of the entire microprocessor system.

In my opinion, one of the main problems of CPU design is to solve the balance between high-speed CPU and low-speed DRAM, in order to improve the overall system performance. And adding cache memory Cache between them can effectively solve this problem. In fact, as early as 1964, the large-scale computer system System/360 system launched by IBM has already appeared in the concept of caching..."

This is a small academic salon held in the living room of Professor Zhao Weiming's house. Every weekend afternoon, a group of students and teachers who love electronic technology gather on the sofa in Professor Zhao's living room to talk freely. Professor Zhao is also willing to broaden students' horizons and cultivate their professional interests through such small gatherings.

Today's topic is the development direction of microprocessors. Li Xuan was invited for the first time. He has been a good listener since the beginning. Among the dozen or so people in the room, he was the only one who was born with a major in electronics and chose to major in computer science.

The major of electronics at CUHK mainly studies hardware, while the study of electronic computing is the computer major of later generations. It mainly studies software knowledge such as programming language and data structure. Although the two are related, they are actually two completely different directions. .

Li Xuan, who was born in software, always joins the crowd of hardware people for fun. Zhao Weiming was also a little curious about his maverick student. He took this opportunity to call him to speak, and test how much ink he had in his stomach, an interesting student who lives in Cao Yingxin and Han.

Li Xuan thought for a while before he talked about his own views. His point of view should not be too detailed or too deep. It has only been a month since the start of school. For a freshman like him, the advanced course of electronics is not even an entry. But he can't say nothing, after all, the purpose of his coming to the party is to show his strength and lay the foundation for establishing his image as a technical bull in the future.

In addition to these, he also has to pay special attention not to pop up some terms that do not exist in this era. For example, the term non-blocking cache seems to have only been proposed in papers in the 1980s, and victim cache only began in the 1990s. Research.

So Li Xuan chose cache as an entry point. With the vigorous development of microprocessors in the 1970s, the problem of slow memory read speed has become more and more prominent. The problem wasn't obvious in the age of 8-bit processors, but it's starting to show up with Intel's release of the 16-bit 8086 processor.

Li Xuan remembers that in 1985, when Intel released the first 32-bit 80386 processor, an external cache was used to solve the memory speed bottleneck. Therefore, his point of view is that it is in line with the next development trend of mainstream processor technology and is more forward-looking.

Zhao Weiming sat on the side sipping coffee, and nodded slightly after hearing Li Xuan's point of view. Before he returned to teach at the Chinese University of Hong Kong, he was originally engaged in the development of microprocessors at RCA. He participated in the core research and development of RCA's only well-known microprocessor, the RCA1802.

This 8-bit processor is known as the originator of the RISC (reduced instruction set) processor. It has low power consumption, high reliability, and can meet the harsh environment of high radiation in outer space. It is the first one to be used in space. microprocessor.

The space probe Voyager 1 launched by NASA in 1977 used three 1802 processors as the core of the system. Before Li Xuan's rebirth, the probe farthest from the earth had successfully flown out of the solar system into interstellar space after a long journey of more than 30 years, but it was still in normal working condition.

"I think RISC (reduced instruction set) is the optimization direction of the computer instruction system in the future. The latest paper published by the research team led by Professor Patterson of Berkeley University not long ago pointed out that the usage rates of various instructions are very different: a 80% of the instructions used in the operation of a typical program are the 20% of the commonly used instructions in the instruction set.

In order to balance the design of a large number of complex instructions that are rarely used, we have greatly increased the complexity of the overall structure design of the CPU, which undoubtedly increases the time and cost of processor design on a large scale..."

When Li Xuan talked, his face was filled with a focused and confident expression, and he unconsciously let others focus on him. Zhao Weiming's eyes fell on him again, and there was a slight wry smile in his surprise.

This is really a good seedling. Although he is a freshman who has just entered the university, he has been able and likes to read the most cutting-edge academic journals in related majors, and the solid theoretical foundation displayed from it is better than the two masters who follow him. Graduate students are no different. Li Xuan's occasional sharp point of view made him have an illusion, as if standing in front of him talking and laughing was a professional foreword who had been immersed in the field of electronics for more than ten years.

Knowledge and skills can be acquired, but vision and insight are a gift from God. Zhao Weiming felt that the rough jade in front of him was the most surprising discovery he had made in the past few years, but when he thought that he was a student majoring in electronic computing research, he couldn't help feeling a little depressed.

Do you want to persuade him to switch to electronics? As for the choice of students' future majors, CUHK's consistent position is to rely on students' own preferences. After all, this is a matter of personal destiny and future, UU reading www.uukanshu. com teachers can give advice and reference, but have no right to decide the future of students.

Zhao Weiming decided to observe patiently for a while. After all, Li Xuan had just entered the university, and there were still more than two months left in the first semester. He still had more than three years to consider carefully. If Li Xuan is really talented in the field of electronics, he does not exclude himself from working in this field, and he will personally go out and clarify the interests with the students at that time.

Li Xuan also noticed Professor Zhao Weiming's surprised expression when he looked at him, and the smile on his face couldn't help but get better. He came here today just to pretend to be forced, and he had spent several days in the library before. The professional journals were like a book from heaven to other freshmen, but for him they were easy to grasp.

Looking at the papers in the journals, he has a general idea in his mind, which views have not been published in this era and can't be leaked, and which views are recent hotspots, he can pretend to be forced, and be a reasoned forward-looking Explore.

And Li Xuan also successfully achieved his goal, which attracted the attention of Professor Zhao. Prof. Weiming Zhao is the only professor in the Department of Electronics at CUHK who specializes in integrated circuit design and has experience in the actual design of microprocessors in large companies. He also has his own team in the school, specializing in the research of integrated circuits, especially microprocessors.

Except for the electronics majors of CUHK, the teachers and students who came to the salon today are all members of his research team. For example, sitting on the bamboo chair on the left, he looks a little dark and thin, and the man who manages is a man with a split head surnamed Cai. One of the compulsory courses for freshmen majoring in electronics - "Introduction to Electronics" is taught by Dr. Cai.