Chapter 466 Three Types of Chips
The other party makes relays and electronic components. Gao Zhendong probably knows what the other party wants to do with 6013, contact material, and it is likely to be used in extremely important projects. Otherwise, the price of tungsten silver materials is still a bit expensive these days, and he would not dare to use it casually.

Gao Zhendong doesn't care much about what other people use the money for; what he cares about is their identity and factory.

For Gao Zhendong, if he wants to evolve direct projection lithography into micro-projection lithography in the future, then he cannot avoid the step of automatic control of the movement of the workpiece stage and mask stage, especially the workpiece stage.

The automatic control of the workpiece stage means that the problem of positioning the workpiece stage during movement comes to the fore.

Fortunately, with the current precision requirements, the motion control of the worktable uses hand-cranked drive gears and screw reduction mechanisms. This has an advantage in that the ratio of its motion state can be determined, such as by directly calculating through parameters such as gear ratios and screw pitch.

This makes it easy. By turning the hand crank into a motor and then directly measuring the rotation of the drive gear, you can directly calculate the final movement distance of the workpiece table.

The best way to measure the rotation of the initial drive gear is undoubtedly to use a multi-turn rotary encoder. It doesn't matter whether it is relative encoding or absolute encoding. The technology between the two is actually common, but absolute encoding is more complicated. For Gao Zhendong's current requirements, a multi-turn rotary relative encoder is enough.

As for the difference between absolute and relative, it mainly lies in the fact that the position of the absolute encoder shaft is strictly corresponding to the output value. The output is a number, through which the angle of the shaft can be determined.

The output of the relative encoder is not a number. No matter how it is output, its core is a signal related to the speed, direction, and rotation angle.

If we use a navigation system as an analogy, the output of an absolute encoder is similar to the output of a GPS, which is the direct result, while the output of a relative encoder is similar to the output of an inertial navigation system, and the final result depends on solving the output.

There is no difference between these two methods, but the application scenarios are different. For example, in motor self-control, absolute encoders are generally not as useful as relative encoders. The frequency signal output by the latter can be directly used to drive the PWM circuit and control the motor speed after simple processing and conversion.

As for this thing, it has only been 80 years since it was produced in China. Before that, since the 50s, it had been imported, and it was not easy to import.

Gao Zhendong wanted to find out from his colleagues at a professional component factory whether he could get encoders now and what kind of encoders he could get stably. Even if they were both multi-turn relative encoders, there were still many differences and tricks.

If you can get a suitable one stably, then you don't have to bother with this matter. If not, then you may have to take some action in this regard.

After thinking for a long time, Gao Zhendong found that it would be better to ask the 12th Ministry of Machine Building directly about this matter. The response there would definitely be faster than the factory, and the situation would be more comprehensive. The appearance of this factory mainly served to remind himself.

After hanging up the phone, Gao Zhendong asked someone to call Xiao Li.

After a while, Xiao Li came running over and shouted as soon as he entered the door: "Teacher, what can I do for you?"

Looking at him, Gao Zhendong suddenly felt a little dazed. It was probably the same when he entered his master's office more than a year ago.

Shaking his head and smiling, Gao Zhendong threw him a cigarette, then walked to the sofa and sat down.

"Two things. First, go to our department and make a connection. There is a factory that needs our 6013 material. Go and make sure this happens. Second, submit a letter to the th Ministry of Machinery to inquire about the current situation of domestic rotary encoders."

The previous matter is full of details and involves confidentiality, so it is just right for Xiao Li to organize and implement it.

The latter is very general and does not require much ability from the person handling it, but it is not suitable for a big show, so it is just right for Xiao Li to do it.

Xiao Li wrote down Gao Zhendong's words, and Gao Zhendong added some relevant information and precautions. He took the notebook and ran away to do his business. Before leaving, he asked Gao Zhendong for the remaining half pack of cigarettes, saying that the teacher's cigarettes were better.
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On December 16, Gao Zhendong received a call from the 12th Ministry of Machine Building. It had nothing to do with the rotary encoder, but rather that there was some progress on the photoresist and optical system that he had asked the 12th Ministry of Machine Building to confirm.

In terms of photoresist, some comrades have already developed a negative photoresist and supporting drugs, and the speed is quite good.

Gao Zhendong doesn’t care whether it is positive lithography or negative lithography. As long as he can determine which one it is, he can start the next step - making a mask.

If you don’t know whether the photoresist you can produce is positive or negative, you can’t proceed with this step. The reason is very simple: the masks of the two are opposite.

As for the other thing, there is also clear news.

The Northeastern Institute of Optics has already developed the first step of the optical system, which is to diffuse a laser beam into parallel light with a diameter of 160mm.

In fact, the optical system in this step is not particularly difficult or complicated. The reason why it took so long is mainly because the optical system is not as simple as putting a few lenses on it.

Even if the first step does not require refocusing, optical paths such as beam expansion, collimation, and homogenization are still indispensable, and engineering issues such as reliability, availability, adjustment, and maintenance must also be considered. It can be said that the design of the optical path is only a part of it.

Although it was completed, there was still some gap before it could be delivered directly. Comrades from the Northeast Institute of Optics still hoped that the proposer of the topic could go and see it in person, which would also facilitate their final adjustments and improvements. However, the Northeast Institute of Optics did not know who the specific proposer of the topic was, so they had to notify the 12th Ministry of Machine Building to convey it.

Gao Zhendong thought about his own time and decided to go there. A month would be enough, and the other projects here would not allow him to leave for a long time.

After calculating the time, he replied to the comrades from the 12th Ministry of Machine Building that he would be there on Wednesday of next week.

After hanging up the phone, Gao Zhendong began to arrange his work.

There is no need to worry about the 6011 battle. Everything is progressing as normal, and the research team has basically solved any minor problems on their own.

The courses at Beijing University of Technology are a problem, but considering that I will most likely be able to go back and forth within ten days, this problem is not so serious. If I arrange it well, I only need to adjust one week of classes.

He arranged to go there next Wednesday for this reason, and leave after class on Tuesday.

The only thing left is to process the mask.

Gao Zhendong took out three sets of drawings, which were the first three types of chips he was going to put into testing.

There are many digital logic circuits, but Gao Zhendong has only chosen these three for the time being. He has other preparations for the others.

——NAND gate, NOR gate, D flip-flop.

The reason for choosing these three devices is that they are the basis of all other devices. In fact, the D flip-flop can also be composed of the first two devices, but its significance is so great and its uses are so wide that Gao Zhendong also made the integrated circuit of this thing first.

AND, OR and NOT are the three most basic logical operations, and all logic circuits can be composed of them.

The NAND gate and NOR gate can complete the above three logic operations. The reason why they are not directly made into AND gates, OR gates, and NOT gates is that in actual logic circuits, NAND and NOR operations are more common than AND and OR operations.

The famous 74 series chips, the first four models, 4~7400, have two NAND gates and two NOR gates respectively.

As for other more complex logical operations such as XOR, XOR, and AND/OR, they can all be decomposed into these three operations.

Among them, the XOR gate is special. Two XOR gates can form an RS latch, an RS latch plus two XOR gates can make a D flip-flop, and two D flip-flops can form an edge trigger.

The eight edge triggers are a 8-byte register.

This is why Gao Zhendong chose these three chips first. They can complete all logic circuits and can be easily made into small-capacity memories, such as registers, temporary memories, etc.

However, it is not possible to use digital components to make large-scale data storage. The area occupied is a minor issue, but it is too expensive. Before the process is advanced enough, the number of transistors per unit area is not enough. At this time, in order to achieve reliable and high-speed data storage, digital circuit storage devices that pay the price of more complex structures cost much more than analog circuits.

Leaving aside the problem of data retention after power failure, a 1kByte data storage device requires eight thousand edge-triggered triggers, a total of 16000 D flip-flops. This is unacceptable and is far inferior to transistor memory, which only requires three transistors to store one bit of data.

Nevertheless, the D flip-flop still provides a convenient means for temporary storage of small amounts of data in engineering applications.

The three chips developed by Gao Zhendong all have 14 pins, which will help Factory 1274 to unify the process and reduce costs.

NAND gate, power supply and ground each occupy one pin, and the remaining 12 pins are divided into 4 groups, each group is a dual-input and single-output NAND gate, so there are 4 NAND gates available on a chip.

The structure of the NOR gate is the same as that of the NAND gate, except that the NAND operation is changed to a NOR operation.

A D flip-flop has two D flip-flops on a chip, which means that if used as a memory, a chip can store 2 bit. If reliability is not required and the D flip-flop is used directly for latching, it can store 1 bits.

This is already a pleasant surprise for today's automatic control personnel. Such a small chip can store two bits of data?
There’s no way around it; memory was just that expensive back then.

With the drawings in hand, Gao Zhendong called Yu Yongnian again and told him that it would be a good idea to let him take care of the processing.

(End of this chapter)