Company memory

Video memory is a very important part of the graphics card, do not underestimate the small pieces of the chip, they are on the performance of the graphics c

Company memory

Video memory is a very important part of the graphics card, do not underestimate the small pieces of the chip, they are on the performance of the graphics card is playing an extremely important role. Today, I'm going to give you a brief overview of some of the parameters of the graphics memory.

The most widely used graphics memory on current graphics cards is SDRAM and DDR SDRAM. SDRAM: SDRAM can work in tandem with the CPU, with no wait cycles and reduced data transfer delays. Advantages: low price, widely used in low-end and mid-range graphics cards DDR SDRAM: DDR is an acronym for Double Data Rate, which is an evolution of the existing SDRAM memory. It is very similar to SDRAM in design and operation. The only difference is that DDR can transfer data on both the rising and falling edges of the clock cycle, while SDRAM can only transfer data on the rising edge, so the bandwidth of DDR is twice that of SDRAM, and the data transfer rate of DDR is twice as fast as that of SDRAM. If the frequency of SDRAM memory is 133MHz, then the frequency of DDR memory is 266MHz. advantage: Both the rising and falling edges of the clock cycle can transmit data, which theoretically has double the performance of SDRAM, so it is widely used in mid-range and high-grade graphics cards.

On the contrary, the once brilliant SGRAM has almost disappeared. The reason for this is cost. Most of the graphics cards now have more than 32M of video memory, and the cost of video memory accounts for a significant portion of the total. SDRAM and DDR SDRAM have a considerable advantage over SGRAM in terms of manufacturing cost, which can effectively reduce the cost of graphics cards with large-capacity memory. Secondly, various mainstream graphics chips, such as GeForce3/GeForce2 series, Radeon series, etc., have been optimized for SDRAM and DDR SDRAM in their design, and these mainstream graphics chips can get good performance with SDRAM and DDR SDRAM. Based on price/performance considerations, it is clearly not wise to use a single SGRAM with a smaller capacity and a higher price point (computer basics).

In addition to the type of memory, there are a number of important technical parameters that are worth looking at, such as speed, actual operating frequency, bit-width, manufacturer, and so on.

Speed: The speed of the memory is usually measured in ns. Commonly, there are 7ns, 6ns, 5.5ns, 5ns, 4ns, and even 3.8ns memory. The corresponding rated operating frequencies are 143MHz, 166MHz, 183MHz, 200MHz and 250MHz, and the calculation of the rated operating frequency is very simple: the reciprocal of the memory speed is the rated operating frequency of the memory. Of course, for some of the better quality video memory, the actual maximum operating frequency of the memory is a certain margin. For example, Samsung's 6ns SDRAM, which was once favored by DIYers, can be overclocked to more than 190 MHz, and 5.5ns SDRAM can be overclocked to 205 MHz, and the trend of overclocking video memory is still going strong today. Overclocking ability is also an important factor when testing the performance of a graphics card. However, we do not advocate sacrificing stability for high speeds, and finding the right balance of performance and stability is what we really need.

Actual operating frequency and equivalent operating frequency. As I mentioned earlier, the nominal operating frequency of the memory is equal to the reciprocal of the memory speed. The fastest memory available today is the 3.3ns DDR memory used in the GeForce3, which is rated at 303MHz, but we often see memory running at 333MHz, 400MHz, and even 460MHz. In fact, these frequencies are equivalent operating frequencies, and because DDR memory transfers data on both the rising and falling edges of the clock, the memory bandwidth is twice as large as that of ordinary SDRAM at the same clock frequency and data bit width. In other words, the actual operating frequency of DDR memory is twice that of ordinary SDRAM memory at the same memory speed. Similarly, the bandwidth achieved by DDR memory is twice that of ordinary SDRAM memory. For example, a 5-ns SDRAM memory operates at 200 MHz, while a 5-ns DDR memory has an equivalent operating frequency of 400 MHz.

Calculation of Data Bit Width and Memory Bandwidth

The data bit width refers to the number of bits that can be transmitted in one clock cycle, which is an important factor in determining the memory bandwidth. It is a key factor in determining the bandwidth of a graphics card, and is closely related to the performance of the graphics card. When using the same type of memory and operating at the same frequency, the larger the bit width, the higher the performance. Graphics memory bandwidth is calculated as follows: operating frequency x data bandwidth/8. The reason for dividing by 8 is that every 8 bits is equal to one byte. Taking the current GeForce3 graphics card as an example, its memory system bandwidth = 230MHz x 2 (multiplied by 2 because it uses DDR memory) x 128/8 = 7.36GB. Data bit bandwidth is a very important parameter for graphics memory and also for graphics cards. The Z-buffer, frame buffer, and texture buffer all take up significant bandwidth resources of the graphics memory during the card's operation. Bandwidth is the 3D chip and local memory transfer data volume standard, this time the capacity of the video memory is not important, will not affect the bandwidth, the same video memory bandwidth of the card using 64MB and 32MB video memory performance difference. Because the bottleneck of the system at this time in the video memory bandwidth, when encountering a large number of pixel rendering work, the video memory bandwidth is insufficient to cause data transmission blockage, resulting in the display chip to wait for the speed of the impact. Currently, graphics memory is divided into 64-bit and 128-bit, and at the same operating frequency, the bandwidth of 64-bit memory is only half of that of 128-bit memory. This is why the performance of the Geforce2 MX200 (64-bit SDR) is far inferior to the Geforce2 MX400 (128-bit SDR). Some graphics card manufacturers have adopted a policy of no disclosure with respect to 64-bit memory, so it is important to ask for clarification when purchasing a graphics card.

Manufacturers: Currently, manufacturers of memory chips are mainly based in Japan, Korea, and Taiwan. The Japanese such as Toshiba (Toshiba), Hitachi (Hitachi), South Korea's main Samsung and Hyundai (HYUNDAI, has been renamed Hynix), Taiwan's representative of the Winbord, EliteMT, EtronTech (Yutron) and so on. Currently on the market graphics cards are mainly used in Samsung, Hynix, Etron, ESMT and other brands of video memory. It should be said that these regular manufacturers of video memory, its performance and quality are guaranteed, both stability and overclocking performance is quite good. For example, the current popular Yutron memory is designed by Taiwan's Jinghao, the famous TSMC foundry production, the use of 0.15 micron advanced processing technology, its DDR module is commonly used in GF3 and other high-end products.

Logos on the memory stick: The logos on the memory stick visualize the technical data of the stick, so it's important to have a basic knowledge of how to identify them.

What does optical storage mean? Computer Basics

Optical storage is affected by the medium on the surface of the disc, the disc has uneven pits, the light shines on it with different reflections, and then converted into a digital signal of 0, 1 becomes optical storage.

Overview of optical storage:

Optical storage refers to the technology, equipment, and products that use laser technology to store data on a disc, such as optical discs (Optical disc), laser drives, related algorithms and software.

From the invention of the ruby laser in 1960, to the introduction of the CD turntable in 1981, VCD in 1993, DVD in 1995, and then BD and HD DVD in 2002, optical storage technology is changing rapidly.

The rapid development and widespread use of optical storage technology has not only provided the conditions for the development and application of computers and multimedia technologies, but has also largely changed the way we entertain ourselves and greatly improved our quality of life.

Of course, there is a protective film on the outside of the CD-ROM, which is generally not visible, but you can see where there is information and no information.

Burning a CD is the same principle, that is, when burning when the light is stronger, burned out different bumps.

Optical disk is just a general term, it is divided into two categories, one is the read-only CD-ROM, which includes CD-Audio, CD-Video, CD-ROM, DVD-Audio, DVD- Video, DVD-ROM, and so on; the other is the recordable CD-ROM, which includes CD-R, CD-RW, DVD-R, DVD-R, DVD + R, DVD+R, DVD+. RW, DVD-RAM, Double layer DVD+R and other types.

With the development of optical technology, laser technology, microelectronics technology, materials science, microfabrication technology, computers and automatic control technology, optical storage technology in the recording density, capacity, data transfer rate, addressing time and other key technologies will have great potential for development. At the beginning of the next century, optical disk storage will be in the diversification of functions, the operation of intelligent will have significant progress. With the development of optical quantum data storage technology, three-dimensional body storage technology, near-field optical technology, optical integration technology, optical storage technology is bound to become one of the pillar technologies in the information industry in the next century.

Principle of optical storage

Whether it is CD-ROM, DVD-ROM and other optical storage media, the storage method used is the same as the floppy disk, hard disk, is in the form of binary data to store information. And to store data on top of these discs, the computer-converted binary data needs to be engraved on the flat, reflective disc with the help of a laser in a data pattern. To recognize the data, the laser-defined pits on the disc represent binary "1's" and the blanks represent binary "0's." DVD discs have smaller recording pits than CD-ROMs, and the distance between the helical storage pits is also smaller. DVDs store data information in very small, tightly packed pits, with a minimum pit length of 0.4 μm, a distance between each pit that is only 50% of that of a CD-ROM, and a track gauge of only 0.74 μm.

The main parts of a CD drive, DVD drive, and a host of other optical storage devices are the laser generator and the optical monitor. The laser generator on the optical drive is actually a laser diode that produces a laser beam of the corresponding wavelength, which is then processed and directed onto the disc, where the reflected signal is then captured by the optical monitor to identify the actual data. If the disc doesn't reflect the laser, it means that there is a small pit, so the computer knows that it represents a "1"; if the laser is reflected back, the computer knows that the point is a "0". The computer can then convert this binary code into the original program. When the CD-ROM is rotating at high speed in the CD-ROM drive, the laser head is moving back and forth under the control of the motor, and the data is being read out continuously.

Computer hardware awareness of what is the computer's power supply

The computer power supply is the 220V alternating current, converted to direct current, and dedicated to computer accessories accessories such as motherboards, drives, graphics cards, and other power supply equipment, is the hub of power supply to the various components of the computer, is an important part of the computer. Most current PC power supplies are switching type power supplies.

Computer Power Supply Classification

ATX Power Supply

The ATX specification is a new motherboard structure standard developed by the Intel Group in 1995, which is an acronym for the English language (AT Extend), and can be translated as AT Extend Standard, and ATX Power supplies can be designed according to this specification. Home computer power supplies currently on the market then follow the ATX specification.

BTX power supplies

BTX power supplies are PC power supplies designed to comply with the BTX standard, but BTX power supplies are compatible with ATX technology, their operating principle and internal structure are basically the same, and the output standard is the same as the current ATX12V 2.0 specification, which is like ATX12V 2.0 specification, taking 24-pin connectors. The BTX power supply is mainly based on the original ATX specification and has derived several power supply specifications, including ATX 12V, CFX 12V and LFX 12V. ATX 12V is an existing specification, the reason why we continue to look at the ATX12V 2.0 version of the power supply can be directly used in the standard BTX chassis. CFX12V is suitable for the total space of the system in the 10-15 liter chassis; we continue to look at the power supply and the previous power supply, although technically unchanged, but in order to adapt to the size of the need to take the irregular shape. Currently defined as 220W, 240W, 275W three specifications, of which 275W power supply to take independent of each other dual +12V output. The LFX12V is suitable for chassis with a system space of 6 to 9 liters, and is currently available in 180W and 200W. BTX is not likely a revolutionary power supply standard, and although the INTEL Group has vigorously promoted it, it has been able to make very little mention of it now because too few vendors have supported it.

Power rating

Power rating is the power that power supply manufacturers mark according to the standards set by the INTEL Group, which characterizes the average output of a power supply's operation in watts, or watt (W) for short. The higher the power rating, the more devices the power supply can carry.

The power of the power supply has a variety of representation practices, in addition to the rated power and peak power, there is also the output power of the statement. Output power refers to the power supply under the necessary conditions for a long time to stabilize the output power. When the power supply actually works, the output power does not have to be equal to the rated power, according to the standard of INTEL Group, the output power will be more than the rated power of the majority, such as about 10%. It should be noted that, in a variety of power nominal way, the rated power is in accordance with the INTEL Group standards, is the most reliable power supply power standard, when buying power supply is recommended to the rated power as a standard of reference and comparison. Unfortunately, some power supply manufacturers do not standardize on power ratings, and there is a problem of false positive ratings. But because the power rating can be quite strict in the nominal way, so too much margin is useless, do not have to pursue too high power rating.

The importance of power

One of the hardest things to find in a PC is a lack of power. Symptoms can be that the motherboard is "not working", software is causing frequent crashes, and the symptoms can be manifested in anomalies with the motherboard, CPU, or memory. These symptoms can be manifested by abnormalities in the motherboard, CPU, or memory, and even sometimes appear to be a problem with the hard drive, CDROM, floppy disk, etc.

Imagine that every part of a PC system has a single source of power ---- that can power it. The power supply must provide a stable, continuous current to all devices without interruption. May be too much or not enough power, the connected devices may not be able to function properly, it seems like a bad thing. For example, memory may not be refreshed, resulting in loss of data files (leading to software errors); the CPU may lock up or randomly reboot; and the hard disk may not spin, or even weirder - it may spin, but it may not be able to process the control

signals properly.

Since so many devices are tied to the power supply, it's only fair to consider the power supply the most important component of a PC hardware system. Unfortunately, most people don't realize this, and when shopping for a power supply, they sometimes prefer an older case (one that has a power supply in it), expecting a "good price". (From experience, this is a common problem.) Older power supplies are not as efficient as they were when they were first used, and do not provide as much power as they claim. Many power supplies are not UL marked and may only "squeeze" 50-75% of the nominal value. Even power supplies in famous cases can be questionable, and we've encountered this on a daily basis.

What is an optical drive in a computer

An optical drive is a product that combines optical, mechanical, and electronic technologies. In the optical and electronic combination, the laser light source from a laser diode, it can produce a wavelength of about 0.54-0.68 micron beam, through the processing of the beam is more concentrated and can be accurately controlled, the beam of light the first step in hitting the CD-ROM, and then by the CD-ROM reflected back to the optical detector through the capture of the signal.

There are two states on the disc, the dimple and the blank, which reflect opposite signals and are simply recognized by the light detector. The information obtained by the detector is simply the arrangement of the dimples on the disc, and there are specialized components in the drive that convert it and calibrate it, and we then look at us to get the actual data. The optical disk rotates at high speed in the drive, and the laser head moves back and forth under the control of the servo motor to read the data.

Categorization of optical drives

An optical drive is a very common accessory in desktop computers. With the increasing use of multimedia applications, the optical drive can become a standard feature in many accessories of desktop computers. Currently, optical drives can be categorized as CD-ROM drives, DVD-ROM drives (DVD-ROM), Combo (COMBO) and burners.

CD-ROM drive: also known as dense disk read-only memory, is a read-only optical storage medium. It was developed using the CD-DA (Digital Audio) format originally used for audio CDs.

DVD drive: is an optical drive that can read DVD disks, in addition to being compatible with DVD-ROM, DVD-VIDEO, DVD-R, CD-ROM and other common formats, for CD-R/RW, CD-I, VIDEO-CD, CD-G and so on to be able to very, very good support.

COMBO optical drive: The "COMBO" optical drive is the common name for the COMBO optical drive. COMBO optical drive is a collection of CD burning, CD-ROM and DVD-ROM as a multi-functional optical storage products.

Burning optical drives: including CD-R, CD-RW and DVD burners, which are divided into DVD+R, DVD-R, DVD+RW, DVD-RW (W for rewritable) and DVD-RAM. burners are similar in appearance to ordinary CD-ROM drives, except that their front panels are generally clearly marked with the three speeds of writing, rewriting and reading. read speeds.

Knowledge of computer hardware: 7, the computer network card

Computer hardware awareness of what is the computer's network card

Computer and the outside world of the local area network connection is through the host box inserted into a network interface board (or in the laptop computer inserted into a PCMCIA card). A network interface board is also known as a communications adapter or network adapter or NIC (Network Interface Card) but nowadays more people prefer to use the simpler name "NIC".

I. Network Interface Card Functions

The NIC has a processor and memory (including RAM and ROM) on it. The communication between the NIC and the LAN is done in serial transmission via cable or twisted pair. In contrast, communication between the NIC and the computer takes place in parallel transmission via the I/O bus on the computer's motherboard. Therefore, an important function of the network card is to perform serial/parallel conversion. Since the data rate on the network is not the same as the data rate on the computer bus, the network card must be equipped with a memory chip that caches the data.

The device driver that manages the NIC must be installed in the computer's operating system at the time the card is installed. This driver will later tell the NIC where in the memory it should store the blocks of data transferred from the LAN. The NIC also has to be able to implement the Ethernet protocol.

The NIC is not a self-contained autonomous unit, because it does not carry its own power supply, but must use the power supply of the computer into which it is plugged, and be controlled by that computer. Therefore, the card can be seen as a semi-autonomous unit. When the card receives a frame with an error, it discards the frame without notifying the computer it is plugged into. When the card receives a correct frame, it uses an interrupt to notify the computer and deliver it to the network layer of the stack. When the computer wants to send an IP packet, it is handed down the stack to the NIC to assemble the frame and send it to the LAN.

As integration continues to improve, the number of chips on a NIC continues to decrease, and although there are now a wide variety of NICs from various manufacturers, their functionality is much the same.

These are the first steps in the process.

(2) Adopt a high-quality main control chip

The main control chip is the most important part of the card, which often determines the performance of the card, so the main control chip used by the high-quality card should be a mature product on the market. Many of the poorer NICs on the market use older versions of the main controller to reduce costs, which can lead to a reduction in the performance of the NIC.

(3) Most of the SMT chip components

In addition to electrolytic capacitors and high-voltage ceramic capacitors, most of the other resistive components are more reliable and stable than plug-in SMT chip components. Instead, most of the inferior NICs use plug-ins, which makes the NIC's heat dissipation and stability not good enough.

(4) Titanium gold-plated gold finger

The gold finger of high-quality NICs is made of titanium gold-plated, which not only increases the anti-interference ability of the NICs themselves, but also reduces the interference of other devices, while the nodes of the gold finger are rounded design. In contrast, most of the inferior NICs are made of non-titanium plated gold, and the nodes are right-angled, which affects the signaling performance.

Three. The main functions of the NIC are the following three

1. Encapsulation and decapsulation of data

When sending, the data handed down from the previous layer is added to the first and last part, which becomes the frame of the Ethernet. When receiving, the Ethernet frame is stripped of its header and tail and sent to the previous layer;

2. Link Management

Mainly the CSMA/CD (Carrier Sense Multiple Access with Collision Detection The implementation of the CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol;

3. Encoding and decoding

That is, Manchester encoding and decoding.

Computer hardware awareness of what is the computer's sound card

Sound Card (Sound Card), also known as the audio card (Hong Kong and Taiwan called the sound card): sound card is the most basic component of multimedia technology, is to do a better acoustic/digital signals to each other a kind of hardware. The basic function of the sound card is to convert the original sound signal from microphone, tape, and CD-ROM to output to headphones, speakers, amplifiers, tape recorders, and other sound devices, or through the Music Instrument Digital Interface (MIDI) to make musical instruments sound wonderful.

Working Principle of Sound Card

The sound card is based on the microphone to obtain the sound analog signal, through the analog-to-digital converter (ADC), with the acoustic amplitude signal sampling converted into a string of digital signals, stored in the computer. Playback, these digital signals to the digital-to-analog converter (DAC), with the same sampling rate reduced to analog waveforms, amplified and sent to the speakers to sound, a technique known as pulse code modulation (PCM).

The main functions of a sound card are as follows:

(1) It can record digital sound files. Through the control of the sound card and the corresponding driver, the signals from microphones, recorders and other sources are captured, compressed and stored in the memory or hard disk of the computer system;

(2) the digitized sound files compressed with the hard disk or laser disk are reduced to high-quality sound signals, amplified and then released through the speakers;

(3) the digitized sound files are processed to achieve a particular audio effect;

the sound card is used as a sound card for recording digital sound files. a particular audio effect;

(4) controlling the volume of sound sources, combining various sound sources, and doing the function of a better reverberator;

(5) using language synthesis technology to read text information aloud through the sound card. Such as reading English words and sentences, play music, etc.;

(6) has a preliminary audio recognition function, prompting the operator to command the computer to work with the password;

(7) provides MIDI function, so that the computer can control multiple electronic musical instruments with MIDI interface. Also, under the action of the driver, the sound card can be stored in MIDI format file output to the corresponding electronic musical instruments, the corresponding sound. The electronic instruments are directed by the sound card.

The main types of sound cards

The development of sound cards has been divided into three main types of interfaces: onboard, integrated, and external, in order to meet the needs of different Internet users, and each of the three types of products has its own advantages and disadvantages.

Board card type: card type products are the backbone of today's market, the product covers low, medium and high grades, the price according to tens of dollars to thousands of dollars ranging. Early board type products are mostly ISA interface, because this interface bus bandwidth is low, single function, occupy too much system resources, has been eliminated; PCI has replaced the ISA interface to become the current popular, they have a better ability and compatibility, support for plug and play on the ability to use, installation and use are very convenient.

Integrated: The sound card only affects the sound quality of the computer, and has little to do with the more sensitive system capabilities of PC netizens.

Therefore, most Internet users are satisfied with the sound card, and prefer to invest in a system that enhances their system capabilities. Although the compatibility, ease of use, and capability of board-based products can meet the needs of the market, in order to pursue a cheaper and simpler, integrated sound cards have emerged.

Such products are integrated on the motherboard, and have the authority to not take up the PCI interface, cheaper costs, better compatibility, and so on, to meet the vast majority of the audio needs of ordinary Internet users, naturally favored by the market. The technology of integrated sound card is also progressing, PCI sound card has multi-channel, low CPU occupancy and other authority also appeared in the integrated sound card, it also dominated the dominant position, occupying the sound card market half of the river.

External sound card: an emerging thing launched exclusively by Creative Group, it is connected to the PC through the USB interface, and has the authority of being easy to use, easy to move, etc. However, this kind of product is mainly used in special applications, and the sound card can be used in a variety of applications. However, these products are mainly used in special environments, such as connecting laptops to do better and better sound quality. There are not many external sound cards on the market at the moment, and the common ones are the innovative Extigy, Digital Music two, and MAYA EX, MAYA 5.1 USB and so on.

Among the three types of sound cards, integrated products are inexpensive, and the technology is becoming more mature, occupying a larger market share. Following the technological progress, these products in the low-end market

also has a very, very big prospect; PCI sound card with continue to become the backbone of the field of high-end sound cards, after all, independent boards in the design of wiring and other aspects of the authority, more suitable for the play of the sound quality; and the authority of the external sound card and the cost of the home PC is not obvious, it is still a fill in the gap in the edge of the product.