MTL - The Science Fiction World of Xueba-Chapter 474 Memory chip

At this time, Xia Peisu, who had not spoken, said: "President Zong, you mean that the future development direction of Xinghuan Technology is to develop a brand new Internet terminal, and rely on this terminal to support a brand new system and commands. Set up an architecture system and form an ecological closed loop? "

Pang Xuelin nodded with a smile and said, "Yes, that's what it means."

Xia Peisu frowned: "If this is the case, during that time, HiSilicon will only have input and no output. How long can you last?"

Pang Xuelin smiled slightly and said, "This is not difficult. Warwick is preparing to enter the mobile communications operator business. Many chips need to be purchased from abroad. HiSilicon can undertake some chips such as DSP chips, ASIC chips, FPGA chips, etc. R & D work. In addition, in the consumer business area, we are also preparing to do flash memory and second-generation synchronous dynamic random access memory. "

"Flash storage? Second-generation synchronous dynamic random access memory?"

Xia Peisu and Ni Guangnan looked at each other and were taken aback.

Flash storage refers to flash memory.

In this era, both technologies are not yet fully mature.

In 1984, Toshiba Corp. Fujioka first proposed the concept of flash memory.

Unlike traditional computer memory, flash memory is characterized by non-volatility, and its recording speed is also very fast.

Intel is the first company in the world to produce flash memory and put it on the market.

In 1988, Intel introduced a 256Kbit flash memory chip.

It is the size of a shoe box and is embedded in a recorder.

Later, this type of flash memory invented by Intel was collectively called NOR flash memory. It combines EPROM (Erasable Programmable Read Only Memory) and EEPROM (Electrically Erasable Programmable Read Only Memory) technologies, and has an SRAM interface.

EPROM means that the content can be erased by special means and then rewritten.

The basic unit circuit (memory cell) is often a floating gate avalanche injection MOS circuit, referred to as FAMOS.

It is similar to the MOS circuit in that two high-concentration P-type regions are grown on the N-type substrate, and the source electrode S and the drain electrode D are led out through ohmic contacts, respectively.

There is a polysilicon gate floating in the insulating layer between the source and drain, and there is no direct electrical connection with the surrounding.

This circuit indicates whether the floating gate is charged or not. If the floating gate is charged (for example, negative charge), just below it, a positive conductive channel is induced between the source and drain, so that When the MOS tube is turned on, it means that 0 is stored.

If the floating gate is not charged, a conductive channel is not formed, and the MOS tube is not conductive, that is, 1 is stored.

The working principle of the EEPROM basic storage unit circuit is similar to EPROM. It generates a floating gate above the floating gate of the EPROM basic unit circuit. The former is called the first-stage floating gate, and the latter is called the second-stage floating gate. Empty grid.

An electrode can be drawn to the second-stage floating gate to connect the second-stage floating gate to a certain voltage VG.

If VG is a positive voltage, a tunnel effect is generated between the first floating gate and the drain, so that electrons are injected into the first floating gate, that is, programming and writing.

If VG is made a negative voltage, the electrons of the first-stage floating gate are strongly dissipated, that is, erased. It can be rewritten after erasing.

The basic unit circuit of flash memory, similar to EEPROM, is also composed of a double-layer floating gate MOS tube.

However, the gate dielectric of the first layer is very thin and serves as a tunnel oxide layer.

The writing method is the same as that of EEPROM. A positive voltage is applied to the second-stage floating gate to make electrons enter the first-stage floating gate.

The reading method is the same as EPROM. The erasing method is to apply a positive voltage to the source and use the tunnel effect between the first-stage floating gate and the source to attract the negative charge injected into the floating gate to the source.

Because the source plus positive voltage is used for erasing, the source of each unit is connected together. In this way, the flash memory cannot be erased by byte, but can be erased in full or block.

Compared to the first NOR flash memory.

The second type of flash memory is called NAND flash memory.

It was developed by Hitachi in 1989 and is considered an ideal replacement for NOR flash memory.

The write cycle of NAND flash memory is 90% shorter than that of NOR flash memory, and its save and delete processing speed is relatively fast.

The storage unit of NAND is only half of NOR, and NAND obtains better performance in a smaller storage space.

NOR type and NAND type flash memory are very different.

For example, NOR flash memory is more like memory, with separate address lines and data lines, but the price is more expensive and the capacity is relatively small.

The NAND type is more like a hard disk. The address line and data line are shared I / O lines. All information similar to the hard disk is transmitted through a hard disk line. In addition, the NAND type has a lower cost and capacity than the NOR flash memory. Much bigger.

Therefore, NOR flash memory is more suitable for frequent random reads and writes. It is usually used to store program code and run directly in flash memory. Mobile phones are large users of NOR flash memory, so the "memory" capacity of mobile phones is usually not large; NAND flash memory Mainly used to store data, such as flash disk, digital memory card are NAND flash memory.

Xia Peisu frowned: "Pang, I have the impression that the flash memory market is not big right now, and the scope of application is also very narrow, and the technology is mainly in the hands of Samsung, Hitachi, Intel and other big manufacturers. Can you make money by doing this? ? "

Pang Xuelin laughed and said: "Academician Xia, you can rest assured. The flash memory market is probably much larger than you think! Some things involve trade secrets. I can't tell you for the time being, but I dare to guarantee that just a flash memory It is enough to make Hisilicon eat a lot.

Xia Peisu and Ni Guangnan glanced at each other, a little surprised at Pang Xuelin's confidence.

Pang Xuelin did not care about the thoughts of these two big brothers, he did not worry about flash memory at all.

Not to mention the memory of mobile phones in later generations, the U disk that will appear in four years alone is enough to support the development of HiSilicon.

In the development process of the world ’s computer industry, storage devices have always been the key to the development of computers. The earliest computers did not have storage devices, used jammed paper, and then replaced them with magnetic tape. Finally, storage devices appeared. It is a floppy disk, the more common one is a 3.5-inch floppy disk, commonly known as A disk, and finally there is an optical disk. Whether the optical disk is the most common storage device within a long time range.

However, the one-time use of the CD also makes people criticized.

Finally, in 1998, a USB flash drive appeared. Due to its large capacity, the USB flash drive can be used repeatedly and plugged in and out at will, making it the most popular mobile storage device until the 1920s and 1930s. The most popular mobile data transmission method in the world.

The USB flash drive originated from China's Netac Technology. This achievement is also regarded as the only original invention patent achievement belonging to the Chinese in the field of computer storage for two decades.

However, Netac has a patent for "U disk", but not a patent for USB flash memory or USB storage.

Because of this, in the real world, Netac has been able to obtain tens of millions of revenue each year through patent litigation, but it has not developed.

Until Pang Xuelin entered the Chinese solar world, Netac still made money by resorting to patent lawsuits and renting houses, which was an insult to a technology company.

Therefore, Pang Xuelin does not intend to leave the U disk patent to the future Netac.

Just a few months ago, Pang Xuelin had filed a USB patent application through Scooper in the United States.

The USB interface is one of the most common interfaces for connecting peripheral devices to a computer host.

In addition to the USB interface, there are interfaces such as parallel bus.

However, the USB interface has a great advantage that makes it very popular in this field, that is, devices with this interface can be plug and play on the computer (plug and play is sometimes called hot plugging).

When the computer is turned on, it is necessary to turn on the peripheral equipment before turning on the power of the host, and the order of turning off is the opposite.

The reason for following this boot sequence is that all peripheral devices must be powered on before the computer starts, and then wait for the host to check these devices one by one and install the corresponding software.

Only in this way can the computer operate normally, otherwise there may be situations where the peripheral device is unavailable or the computer cannot recognize the peripheral device.

The appearance of the USB interface has changed this situation. If a device is a USB interface, it can be plugged into the computer host at any time regardless of the state of the computer at this time, and if you want to remove this device, just follow the specifications The device can be safely removed from the computer by operation. This undoubtedly provides great convenience for people's study and life.

Historically, USB technology was invented by Intel ’s chief system technician Bart. Intel finally decided to open this technology for free, and cooperated with companies such as Microsoft and Compaq to determine it as a universal standard interface for computers.

After applying for a USB patent, Pang Xuelin decided to open it for free, and through Don Valentine's relationship, lobbying Compaq, Microsoft, Intel and other companies to accept this unified standard interface.

The feedback we have received so far is good. If nothing unexpected happens, from next year on, most PCs produced by computer manufacturers will have a USB interface.

With this kind of foreshadowing, if Pang Xuelin withdraws from the U disk in the future, no company can bypass the patent he has from a technical perspective.

At that time, HiSilicon can also get a good return on the success of the U disk in the field of memory chips, and form a virtuous cycle between research and development-production-sales.

Of course, Pang Xuelin will not talk to Xia Peisu and Ni Guangnanming now.

Seeing Pang Xuelin's confident look, Xia Peisu opened his mouth and finally said nothing.

To say that in the field of research and development, Xia Peisu is confident to beat this young man in front of him.

But in terms of doing business, Xia Peisu had no say in front of Pang Xuelin.

Have you seen that even RM Daily has publicly declared that Pang Xuelin is the younger generation of entrepreneurial leaders?

Pang Xuelin's various operations in the Xinghuan CVD marketing process, even Xia Peisu, who is so absorbed in the academic field, have heard of it.

This shows that Pang Xuelin's popularity in the country.

At this time, Ni Guangnan said: "President Zong, what do you mean by the second-generation synchronous dynamic random access memory?"

Synchronous dynamic random access memory refers to SDRAM.

This is a dynamic random access memory (DRAM) with a synchronous interface.

Usually DRAM has an asynchronous interface, so that it can respond to changes in control input at any time.

SDRAM has a synchronous interface, which will wait for a clock signal before responding to control input, so that it can be synchronized with the computer's system bus. The clock is used to drive a finite state machine to pipeline the incoming instructions.

This allows SDRAM to have a more complex operating mode than asynchronous DRAM without a synchronous interface.

Pipeline means that the chip can accept a new instruction before processing the previous instruction. In a write pipeline, the write command can be executed immediately after the execution of another instruction, without waiting for the data to be written to the storage queue. In a read pipeline, the required data arrives after a fixed number of clock frequencies after the read command is issued, and this waiting process can issue other additional commands. This delay is called latency, and is an important parameter when buying memory for a computer.

SDRAM is widely used in computers, from the initial SDRAM to the next generation of DDR, then DDR2 and DDR3 entered the mass market, and in 2015 DDR4 entered the consumer market.

What Pang Xuelin has to do is DDR memory.

The official name of DDR memory is DDRSDRAM (DualDateRateSDRAM). As the name implies, it is a double-rate SDRAM. It is known from the name that it is an upgraded version of SDRSDRAM. DDRSDRAM transmits a signal on the rising and falling edges of the clock cycle, so that its data transmission The speed is twice that of SDRSDRAM, and it does not increase power consumption. As for the addressing and control signals, it is the same as SDRSDRAM, which is only transmitted on the rising edge. This is a compromise to the compatibility and performance of the memory controller at that time.

DDRSDRAM uses 184pin DIMM slots, and the foolproof notch changed from two in SDRSDRAM to one in UU reading www.uukanshu.com. The common operating voltage is 2.5V. The frequency of the first generation DDR memory is 200MHz, and then DDR- was slowly born. 266, DDR-333 and the mainstream DDR-400 of that era, as for those running at 500MHz, 600MHz, 700MHz are considered overclocking, when the DDR memory first came out there was only a single channel, and later appeared to support dual-pass chipset, let The bandwidth of the memory is directly doubled. If two DDR-400 memories form a dual channel, it can basically meet the FSB800MHz Pentium 4 processor, and the capacity is from 128MB to 1GB.

DDR memory has achieved a complete victory in the war against RDRAM, so a lot of motherboard manufacturers have chosen to launch chipsets that support DDR memory. The motherboard market at that time was quite lively, not only Intel and AMD were singled out, There are also NVIDIA, VIA, SiS, ALI, ATI and other manufacturers, so there are quite a lot of CPUs that can use DDR memory, Socket370 Pentium 3 and Celeron, Socket478 and LGA775 Pentium 4, Pentium D, Celeron 4, Celeron D, as long as you want Core 2 can actually be plugged into some 865 motherboards to use DDR memory, AMD's SocketA interface K7 and Socket939, Socket754 K8 architecture products can use DDR memory.

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