What is the difference between the serial port and the hard disk?

Do not often contact computer friends may be a lot of small computer knowledge do not understand, today's editor in the QQ group of computer enthusiasts have found a friend asked a relatively simple, but the novice friends generally do not pay attention to the problem: what is a serial disk, what is the same port hard drive. Whichever speed is faster and so on. The author found that a lot of friends do not understand or know the incomplete, editing here to release some hard disk serial port and the mouth more detailed introduction. Hope to be helpful to friends who are in touch.

For the sake of understanding, have friends to introduce the difference between serial and port hard drives:

Colloquially speaking, the serial port describes a lane, and the mouth is 8 lanes

8-bit (one-byte) data can be transmitted at the same time.

But not and tundish, due to the interference between 8-bit channels. Transmission is limited by speed. And when the transmission goes wrong, 8 bits of data are retransmitted at the same time. There is no interference in the serial port, transmission error after the hair can be a. So hurry up and tundish. Serial hard disk is so people pay attention to.

Below we share the next serial hard disk and the same port hard drive data cable difference, the following figure:

Serial port and parallel port hard drive data cable contrast

　　"Serial hard disk" and "Mouth hard disk" difference
as technology matures, more and more motherboards and hard disks are starting to support SATA (Serial ATA), and SATA interfaces are gradually replacing the traditional pata (parallel ATA) trend. What is the difference between SATA and PATA in transmission mode, and what are the advantages of SATA relative Pata? This is the topic that this article needs to discuss.

　　What is Parallel ATA
ATA is actually an interface standard for IDE devices, and most hard drives, optical drives, floppy disks, and so on are using ATA interfaces. For example, the majority of friends now use parallel ATA interface of the hard disk, it should be 80-pin line of the interface is more familiar with it? Usually we talk about the hard disk interface, we have to mention what ultra-ata/100, ultra-ata/133, what does this mean? This tells us that the maximum transfer rate for the hard drive interface is 100mb/s and 133mb/s, and the hard drive is being transferred in parallel, WWw.PC841.CoM so we also call this kind of hard disk parallel ATA.

　　What is Serial ATA

Serial ATA full name is Serial ATA, which is a new interface standard. The main difference with parallel ATA is the way it is transmitted. It is different from parallel transmission, it has only two pairs of data lines, using point-to-point transmission, in order to transfer the data in a higher speed than the parallel transmission. The current Serial ATA interface transfer rate is 150mb/s, and this value will grow rapidly.

　　The difference between Serial ATA and parallel ATA transmissions
For example, A and B teams are moving packages in a game, and a represents a parallel ata,b for serial ATA.

At the beginning of the game, a dispatched 40 men to carry the parcel, and B sent only a lorry to carry it. In a back and forth they carry the same number of parcels, we can be very clear that the final result, of course, is the Van B team to carry the package, because the speed of the truck faster than people walk a lot more. Similarly, serial transmissions are similar to the rate of parallel transmission.

Back in reality, the parallel ATA interface now uses a 16-bit two-way bus that can transmit 4 bytes of data during 1 data transfer cycles, while the 8-bit bus used by Serial ATA can transmit 1 bytes per clock cycle. These two modes of transmission, in addition to the transmission speed of each clock cycle is not the same, there is also a fundamental difference in the mode of transmission, where the serial ATA data is transmitted by one packet after another, while parallel ATA transmits several packets at a time, although more data is transferred by parallel ATA on the surface of a cycle. But let's not forget that serial ATA clock frequency is much higher than the parallel clock frequency, that is, the number of times in a unit time to carry out data transmission more, so the transmission rate of Serial ATA is higher than the transmission rate of parallel ATA, and there is more room for improvement in the future.

　　Why we have to adopt Serial ATA interface
the answer is simple, of course, to get a higher rate of data transfer. With the increasing of the data transmission rate of the current equipment requirement, the working frequency of the interface is more and more high, the parallel ATA interface gradually exposes some design "mishap", among which the most fatal is the signal interference of parallel circuits. Because the traditional parallel ATA uses the parallel bus transmission data, must request the data synchronization on each line, if the data cannot synchronize, can appear repeatedly reads the data, causes the performance to descend, even causes the reading data to be unstable.

And the use of line design data line, it is the data can not be read faster "culprit." Because of the high speed signal being transmitted, a weak electromagnetic field is generated around each cable, and then affect the data transmission in other data lines, but also because of the length of the cable and voltage changes and constantly changing, with the bus frequency, the strength of the magnetic field is more and more large, the impact of signal interference is more and more obvious.

Theoretically, the working frequency of serial transmission can be increased infinitely, and serial ATA is to improve the interface transmission rate by increasing the working frequency. As a result, serial ATA can achieve a higher transmission rate, while parallel ATA is difficult to achieve such a high transmission rate until the crosstalk problem is effectively resolved.

Parallel ATA interface is restricted by its design in bus frequency. And can not blindly upgrade, and as the data transfer rate of higher requirements, the current fastest parallel ATA interface ATA133 frequency of 33MHz, this has almost reached the limit of the parallel interface, and then continue to transform the line has not been realistic. So it is imperative to launch a new interface.

　　Besides the high transmission rate, what are the advantages of SATA?
1. More reliable data
in the verification aspect, the parallel ATA bus is just a simple CRC check, once the receiver found that the data transmission problem, they will discard them, and then request a postback, if the data signal interference too large, it will seriously affect the performance of the hard disk.

The Serial ATA can improve the reliability of the bus by CRC checking the command and CRC checking the data.

　　2. Easy connection
in the data line, parallel ATA with 80-pin line, Serial ATA due to the use of point-to-point way to transmit data, so only need 4 lines to complete the send and receive function, plus the other three ground, a total of only 7 physical connection to meet the needs of data transmission. Due to the low transmission data lines, SATA in the physical circuit of the electrical performance of the interference greatly reduced, which also ensures the future disk transmission rate further upgrade.

Compared to parallel ATA, the data cable of Serial ATA is finer, which makes the wiring inside the chassis easier to organize, helps the airflow inside the chassis, and makes the cooling inside the chassis better. In the same way, Serial ATA has the advantages of using a non-row pin design interface and supporting hot-swappable features.

　　Does parallel ATA exist after Serial ATA is launched?
Overall, the advantages of serial ATA are obvious. Of course, there are some relatively low-speed devices in the use of parallel ATA, such as optical drive, burner and other devices, parallel ATA transmission rate can be satisfied with the need, so, parallel and serial will coexist for a long time. Of course, Serial ATA supports all ATA devices, as well as devices such as optical drives, but Serial ATA is now used first on the hard drive and will support more storage devices in the future.

At present, we use most of the hard disk is the serial STA, STA in the older computer sometimes can also see the previous and the mouth of the hard disk, with the development of science and technology, and the mouth of the hard drive is gradually out of our sight, so everyone in the process of DIY assembly of the computer can now buy is the serial port hard disk, But as a computer enthusiast we still need to master the relationship between the serial-port hard drive.