Cao Changjiu has had a very happy past few days, and it is different to have a few like-minded fox friends with him. There are snacks to eat constantly, such as Danpi, such as White Rabbit Milk Candy, which is a memory in a long-term dream, and it is the first time to enjoy it in reality.

As for the snack provider, it was a big surprise, it was actually a big man.

The big man's surname is Li, his name is Mengyang, and he is tall and tall, but he has this greedy mouth, which is really incredible for a long time. But this kid has a good personality, when others praise him, he smiles, and he doesn't get angry when others say two words about him. It's just that the voice is a little loud, and others are always startled by his sudden high decibel next to him, which is really not conducive to environmental protection.

The other three were just invited by Big Li to help, and they all had their own things to do, and they didn't meet Chang Chang in the past few days. However, Li Dazi soaked with Cao Changjiu every day, and everyone else was transferred by Director Mei to tackle key problems, leaving him alone to hold the defensive position.

Wang was busy with ECL high-speed integrated circuits and didn't have time to care for a long time. Cao Changjiu just let it be, the key is that there are good things here that he didn't even expected.

The name of the Shanghai Metallurgical Institute sounds like a steel enterprise, but in fact, it is a big mistake, specializing in semiconductor manufacturing technology, and the task of imitating the 8080 microprocessor issued by the state is what they took over.

Cao Changjiu also just knew that there was such a thing, and he asked Li Mengyang: "Big man, you are not tired of drawing like this?"

"I'm not tired, I don't have any other hobbies, I just like to study these digital circuits. As long as I understand what a circuit is for, my heart is like eating ice cream, and it is very refreshing. Especially for this year's task, the director will take the microprocessor he got from Lao Mei for us to copy, and I can't ask for it. ”

Cao Changjiu patted the mosquitoes while looking at Li Mengyang's drawing and said, "You didn't make this thing, where did you get it?"

Li Mengyang put down his pen and said mysteriously: "It is said that the true state secrets were bought by patriots, and it took a lot of hard work to bring back the latest products in China, and an integrated circuit the size of a fingernail can be used as an entire computer, which is high-tech." We are now preparing to copy it, and I heard that the Germans and Lao Maozi are also working on this thing, but they have not succeeded. There were only 4 samples, and last month we planed two of them to restore some of them. ”

Cao Changjiu listened with relish: "How can this integrated circuit be copied so small?"

Li Mengyang said proudly: "Although you are a computer, you don't understand this, the so-called integrated circuit, is to use printing technology to copy the circuit pattern on the silicon wafer, and then through corrosion, metal plating, ion implantation and other processes to make those patterns become the circuit structure of the transistor." To put it simply, it is a miniature transistor circuit, but in fact, the function is the same as that of a large one. ”

Cao Changjiu interrupted and said: "Nonsense, I know this, I just often hear that slices can copy integrated circuits, what's going on, you tell me." ”

Li Mengyang said: "Slicing is the jargon of the photography industry, and it is just borrowed. The integrated circuit is too small for the human eye to see, and even if it is seen, it is impossible to copy it one by one, and if you want to copy an integrated circuit, you have to rely on reverse engineering. Reverse engineering knows, yes, that's good. The manufacturing of integrated circuits is generally to make the designed circuit into a reticle, and use the photolithography process to make the pattern on the silicon wafer. Therefore, imitation integrated circuits must have a mask. We planed the film is the opposite, open the package of the integrated circuit, take pictures of the integrated circuit with a high-resolution camera on the shelf, and use the pickling to remove the metal wires on the integrated circuit, and then get a layer of reticles, and then pickle and take pictures, and then many times in turn, we get all the reticles of manufacturing this integrated circuit, with which you can copy the integrated circuit in large quantities, you understand. ”

Cao Changjiu sighed: "I see, it's not complicated, a fool can do it." ”

Li Mengyang: "Of course it's simple for you to do this, as long as you have enough materials and tools, there's nothing that can't be copied." The key is that you have to understand how it works, otherwise you'll always have to slice and follow people's butts. ”

Cao Changjiu nodded: "So the country wants you to imitate it, and you have to understand it thoroughly, isn't it." ”

Li Mengyang shook his head: "Yes, we have restored the ALU unit design from the copied layout, it's amazing." ”

Cao Changjiu: "In general, I don't recognize it at a glance, and it's nothing!"

Li Mengyang: "I think it's very challenging, what is the name of the company that makes this chip, yes, Intel, it's still full of level, at least I haven't figured out all the things yet." ”

Cao Changchang said: "Generally, there is a problem with the overall design direction, basically no forward-looking, and it will be eliminated soon, and it will be much more efficient for me to do it." ”

Li Mengyang didn't believe it: "No, I think this is amazing, such a small thing integrates more than 6,000 transistors, and we have only just reached this level now." This is a product from three years ago, with 120,000 calculations per second, which is almost comparable to our domestic small computer, and I think it is very promising. ”

Cao Changjiu: "Let's study the principle of it first, and then discuss what this thing is." You see, I'm drawing a diagram of how the 8080 accesses external devices, and it should be using a separate address space specifically for peripherals, which is a different address space than the physical address space of the microprocessor's local memory, where all the input and output ports of the peripherals are addressed. The microprocessor accesses the address unit in this space by setting up special input and output instructions, which is known as the 'I/O mapping method'. This is its main shortcoming, the storage address space that can be accessed is too small, with 8080, the eight-bit microprocessor can only access 16kB address, which greatly reduces the computing efficiency. ”

Li Mengyang was dumbfounded when he heard this: "According to what you say, it's really like this, so how can you avoid it?"

Cao Changjiu drew another diagram: "There are many kinds, this is the one I think, that is, only one physical memory address space is realized." In this case, the physical address of the peripheral input and output ports is mapped to a single physical address space of the CPU and becomes part of the memory. In this case, the microprocessor can access the input and output ports of the peripherals as if they were a memory cell, without the need for a dedicated peripheral input and output instructions. I call this the 'memory-mapped way'. ”

"Of course, this is just a shortcoming in its architectural application. As for the other areas that could be improved, given the scale of 6000 transistors, I can make a microprocessor that is 3 times faster than the 8080. ”

Li Mengyang obviously didn't believe it: "You just blow it, we can do it on such a large scale, you can do it if you have the ability!"

Cao Changchang's heart moved, and he couldn't help but have many ideas.

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The alcohol is surging, and I can't hold it at night, and I continue to code it during the day at night.