Chapter 848: The Russians’ Confusion
"Mr. Davari, this computer seems to be a little different from the DJS-60D." Another Russian was very familiar with the DJS-60D. He was Comrade Vitali, who imitated the DJS-59.

As a top computer expert in this field, Vitali was naturally invited to join this research group, knowing that this new type of switch was computer-controlled. He was one of the people who was most familiar with Southern Comrade Computers.

It is indeed different. After all, switches are different from ordinary computers. Gao Zhendong guided his comrades in the Institute of Communications to design some dedicated circuits to complete some special functions. Moreover, the chips used in these circuits have rather strange input and output rules, and they can only be tested with the help of programs.

There were no proper logic analyzers these days, and these dedicated circuits were the first hurdle in some small operations.

"I can see it, but I am confident that sometimes the worst that can happen is we can use the black box mode, regardless of the internal components. We can analyze the functions based on other circuit parts, and maybe directly making this functional circuit can meet the requirements. It doesn't matter if it's not integrated. If it doesn't work, we can grind it. It doesn't matter if the quantity is not large." With the angle grinder as a backup, the other person didn't think it was a big problem.

He is Anatoly, who is responsible for replicating DJS-59 together with Vitali, and is the one who is more responsible for the specific work and is very familiar with this aspect.

At this time, someone had already followed the connection and found the memory of this programmable switching system.

This control computer is based on DJS-60D. Anyone who is familiar with its interface can easily find the memory location based on experience, and can distinguish between program memory and running memory.

Running memory looks... a little off.

But this is not a big problem. The biggest problem is that there is no program memory!
Anatoly looked at the running memory and turned to look at his colleagues.

"Davri, why did they connect two batteries to the operating memory? And they said they couldn't disconnect them? And there was no program memory?"

A colleague shrugged. "Maybe it's for high reliability. They always have endless new ideas. Ha, they are really willing to spend money to store the program directly in the running memory."

This kind of operation exists when using magnetic core memory and is very common. There is no distinction between running and program memory. Anyway, the magnetic core is retained after power failure, and the addressing space and physical structure are actually all put together.

When the Southern comrades developed a general computer architecture, they separated the two. The program memory could use low-speed and cheap media, and the running memory could use high-speed media such as RAM chips, which achieved a good balance between cost and speed.

But unexpectedly, Comrade Nan Fang restored this structure on the programmable switching system, perhaps for the sake of operating speed and business recovery speed, so that it can be put into use immediately after power-on.

This method is very expensive compared to magnetic tapes and the latest floppy disk drives they saw not long ago, especially the larger the program capacity, the more prominent this problem is. And the program capacity of the program-controlled switch is not small.

"Maybe it's for running speed. By the way, since the running memory and program memory are combined, they need to be maintained when the power is off, otherwise the program will be lost. Maybe these two batteries are for this purpose. The reason for two batteries is one main and one backup, in order to improve reliability and facilitate battery replacement when necessary," someone analyzed.

Batteries are rechargeable and generally do not need to be replaced once they are connected to an external power source. However, they can break down or be left without power for a long time. At this time, having a primary and a backup battery becomes useful.

The Russians know very well that RAM will lose data when power is lost. So in this two-in-one structure, in order to ensure that the program is not lost, a battery is indeed needed to maintain data in the event of a power outage. RAM does not consume high power, and the battery can retain its data for a relatively long time.

We have to admit that these old Russians' thinking is completely correct. At first glance, they have analyzed the situation and reasons in this regard.

"Really?" Anatoly looked at the not-so-big battery, then turned his gaze to the pile of operating memory chips with obviously different packages on the circuit board, and had a bad feeling in his heart.

That kind of package looks very much like epoxy resin package. My colleagues in the south gave it a name, called "cow dung package". Looking at those chips, I have to admit that the description given by our comrades in the south is very vivid.

But here's the thing, why would they use this bullshit packaging on running memory?
Their RAMs are all in standard packages, and can be directly assembled using standard chips. Why would they go to the trouble of using this package? This is disadvantageous to both manufacturing and management.

Unless... they have a reason to do so, or the RAM chips they use in the programmable switches are somewhat different from ordinary ones and cannot use ordinary RAM chips in standard packages.

Following this question, he even thought of a more important question: why do they use such an expensive memory structure? Large-capacity floppy disk + small-capacity RAM, this is the solution that can take both cost and performance into consideration.

I can think of this solution. As the inventor of these devices, Comrade Nan Fang cannot be unaware of this. Even if the people who make programmable switches cannot think of it, their computer researcher Davari Gao must be able to consider this.

Thinking of this, Anatole felt even more uneasy.

"Can the program be read out?" Regardless of whether the program is read from the program memory or is originally in the running memory, as long as the program enters the running memory, it must be executable. Reading it out will be of great use. This judgment made him put his worries to rest.

"We'll try," a technician replied.

The most important thing, reading the program, is naturally given the highest priority.

The people in the Russian imitation group are all top-notch. The reading work was quickly attempted within a day. The memory read and write interface is universal, and this work is not difficult to complete.

"Sukabulie! The programs and data read out are completely messed up!" An old Russian man in charge of data reading cursed loudly after looking at the preliminary decompilation results.

"Impossible! The programs and data in the running memory cannot be encrypted. The computing unit simply does not have the ability to encrypt and decrypt data on the fly." Anatoly retorted. He knew very well that there was not much difference in actual structure between DJS-60D and DJS-59.

Not to mention now, even decades later, the data in the running memory will not be encrypted.

After saying that, he carefully observed some of the data. His solid foundation and rich experience made him feel that these seemingly chaotic instructions and data actually followed certain rules.

"They've messed up the process!" Anatoly exclaimed.

Although the decompiled results seemed incoherent, Anatoly could still see that this chaotic result was actually part of a huge program, but it was completely disrupted and had no practical value at all.

"Out-of-order addressing mapping?" As one of the two top people in computer science here, Vitali didn't know how to describe this technology, so he used a phrase he invented to describe it.

Although he had invented the phrase, Anatoly understood what he meant.

"Yes, that's right! It's the out-of-order mapping of addressing! This can't be encrypted data. If it is encrypted data, it is impossible to decompile so many normal-looking single instructions. From this point of view, it is basically certain that it is still plain text. Moreover, the computer's arithmetic unit cannot support decryption at runtime. That is a huge waste of computer computing power."

Anatoly gave his analysis. The encryption he mentioned was not a simple method like replacing letters or circular shifting, which would be the same as no encryption. It was a serious encryption and decryption, similar to the data encryption algorithm that Gao Zhendong had developed for the National Defense Work Committee, which was very computing-intensive.

Vitali nodded in agreement. "So they used a simple method to scramble the addressing address and the actual address of the running memory and remap them. In this way, although the data read out by the normal read instruction is plain text, it is completely scrambled plain text. For programs with extremely high requirements for the sequential structure, it also achieves the encryption effect."

Anatoly thought he had found the key to the problem and laughed.

"Hahaha, no matter how they scramble it, there are two places where this mapping relationship must exist. One is where the decoder sends instructions to the instruction fetcher to read, and the other is where the memory address is decoded. As long as we find these two locations, any one of these two inverse mapping relationships can help us solve the mystery."

Vitali patted his shoulder heavily: "My Davari, you are so right!"

The other comrades nearby looked at the two of them and were very impressed. These are our top computer experts, Hulla!
Then the two looked at the circuit board and fell into deep thought.

Who are those chips with shiny polished tops on the main control board?
Forget it, this side is too complicated and there are too many unknowns, so let’s just look at the memory side.

Memory chips all look the same, and the rest is mostly related to this out-of-order mapping address decoding function. Simple!
Then, they looked at the pile of "cow dung" that looked exactly the same on the storage board and fell into confusion.

Who the hell is this?
After a brief moment of confusion, Comrade Anatoly raised his head.

"Don't worry. We will analyze their circuit carefully and find out the functional structure of this part quickly after spending some time according to the circuit direction."

Vitali and other comrades nodded, it made sense.

But is this really the case?
(End of this chapter)