Weak current College】 【serial hard drive and the difference between parallel hard drive.

As the technology matures, more and more of the motherboard and hard drive are beginning to support SATA (serial ATA), SATA interface gradually have to replace the traditional PATA (parallel ATA). So SATA and PATA in transport mode, what is the difference between the relative PATA, SATA and what advantages? this is the topic of this article.

What is parallel ATA

ATA is actually an interface standard for the IDE devices, most of the hard drives, optical drives, floppy drives, and so on are using ATA interface. For example, now most of my friends use the parallel ATA interface hard disk, should it 80-pin ribbon cable for the interface is familiar with the? we say to the hard drive interface, you have to mention what Ultra-ATA/100, Ultra-ATA/133, this means what? this tells us the hard drive interface maximum transmission rate is 100 MB/s and 133MB/s, and the hard drive is a parallel approach to data transfer, so we have such a hard drive is called parallel ATA.

What is serial ATA

Serial ATA is the full name, SerialATA is a new interface standards. And parallel ATA's main difference is that it transports. It and the parallel transmission, only two pairs of cables, using point-to-point transmission than parallel transfer higher speed data packet transmission. Now the serial ATA interface, transfer rate 150MB/s, and the value will grow rapidly.

Serial ATA and parallel ATA transfer difference

For example, compared to exaggerate A, B teams in the competition for handling packages, A representative of the parallel ATA, serial ATA B representative. The start of the game, A sent 40 personal human handling package, and B only sent a truck to transport. In a back and forth, they carry the same number of packages, you can clear the final result is, of course, the use of the B team van parcel shipping finished first, because goods faster than walking speed more quickly. Similarly, the serial transmission rate than parallel transmission is high in cases such as this. Back to Earth, the parallel ATA interface using a 16-bit bidirectional bus, 1 data transmission cycle can transfer 4 bytes of data, and serial ATA uses 8-bit bus, each clock cycle can transfer 1 bytes. These two transmission modes except in each clock cycle transfer speeds are different, in the transmission mode on the fundamental difference that serial ATA data is then a packet transmission, and parallel ATA is a simultaneous transmission of several packets, although on the surface, a cycle of parallel ATA transfer data more, but let us not forget that serial ATA's clock frequency than parallel clock frequency is much higher, i.e., the unit of time, data transfer, the number of cycles, so the rate is higher than the serial ATA and parallel ATA transfer rates, and the future still more headroom.

Why should we adopt the serial ATA interface

The answer is simple, of course, in order to obtain a higher data transfer rates. As the demand for the current device, the data rate is getting higher and higher frequencies, interface is getting higher and higher, the parallel ATA interface has revealed some of the design of a "hard wound", one of the most deadly is parallel lines of signal interference. Because traditional parallel ATA uses a parallel bus data transfer, you must require each line of data synchronization, if the data to be synchronized, repeatedly read data, resulting in a performance decrease, even to read the data.

With wire design is the data cable, data read is not faster "culprit". As a side-by-side high-speed signal transmission, each cable of the electromagnetic field surrounding produce weak, which in turn affects other data cable transfer of data, but also because the cable length and voltage changes constantly changing, with the bus frequency of lifting, magnetic field strength is increasing, the impact of signal interference and more obvious.

Theoretically the serial transmission frequency can be unlimited, serial ATA is by increasing the operating frequency to improve interface transfer rates. Therefore the serial ATA can achieve higher transfer rates, and parallel ATA in the absence of effective solutions to signal crosstalk problem before, it is very difficult to achieve such a high transfer rate.

Parallel ATA interface in the bus frequency is its design, and will not be able to unilaterally raise, and with the requirements of the data transfer rate, currently the fastest parallel ATA interface ATA133 33MHz frequently, this has almost reached the limit of the parallel interface, and then continue the renovation has not realistic. So the new interface is imperative.

In addition to the higher transfer rates, what benefits do SATA?

1. data reliability

The validation context, parallel ATA bus just a simple CRC, once the receiving party discovery data transmission problems, it will discard the data, and then request a resend, if the data signal interference is too large, it can seriously impact the performance of your hard disk.

The serial ATA is the command for CRC, also for grouping data, thereby improving the CRC checksum of reliability.

2. wiring simple

In data lines, parallel ATA uses 80-pin cable, serial ATA as a point-to-point transmission of data, so you only need 4 lines to complete the send and receive functions, plus the addition of three ground, a total of only 7 physical connection can meet the needs of data transmission. As a result of the transmission cable less, making the physical line of SATA in the electrical performance of interference significantly reduce, this also ensures that future disk transfer rate further improved.

And parallel ATA, serial ATA data cable is smaller, it also makes the chassis internal wiring easier consolidationTo contribute to the flow of air inside the chassis, making the chassis internal heat better. Similarly, the serial ATA is a non-row of pins designed interface and supports hot-swap feature, etc.

Serial ATA launched after the existence of parallel ATA also?

Overall, the serial ATA's advantage is obvious. Of course, there are still some relatively low-speed devices to use parallel ATA, such as optical drives, burners, and other equipment, parallel ATA transfer have to meet the need, therefore, parallel and serial will be a very long period of time. Of course, the serial ATA supports all ATA devices, or devices such as CD-ROM, serial-ATA present will first use on your hard disk, the future will support more storage devices.