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6022136 2009 年 09 月 30 日 07:47 Reading (loading. ..) Comments (0) Category: Personal Diary
sync - what you told me to go to dinner, I heard you went to dinner; If you do not hear, you will not stop calling until I tell you hear, it went out to dinner.
asynchronous - that you call me,
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also called synchronous, asynchronous message
the difference between synchronous and asynchronous transfer
1, character-oriented asynchronous transfer is transmitted, and bit-oriented synchronous transmission is the transmission.
2, asynchronous transmission and synchronous transmission unit is the character of the unit is frame.
3, asynchronous transfer through the start and end of the start and stop character codes to seize the opportunity to re-sync, and synchronize data transmission is based on extracting synchronization information.
4,
louis vuitton monogram, asynchronous transfer of timing require lower simultaneous transmission lines are often coordinated by a specific timing clock.
5, asynchronous transfer relative to the synchronous transmission efficiency is low.
synchronous transfer mode the sender and the receiver clock is uniform, character and character transmission is synchronized between the free interval.
asynchronous transfer mode does not require the sender and the receiver clock exactly the same characters and the characters between the transmission is asynchronous.
in the network communication process, the communicating parties to exchange data, you need a high degree of collaborative work. In order to properly interpret the signal, the receiver must know exactly when the signal should be received and processed, so time is critical. In a computer network, known as bit synchronization timing factors. Synchronization is in accordance with the sender to the receiver to send the start and end of each bit time and rate to receive data, or will cause errors. Usually synchronous or asynchronous transmission of bits for synchronization.
1. Asynchronous Transfer (Asynchronous Transmission): asynchronous transfer will be transmitted bits are divided into groups, group 1 can be 8 characters or longer. The sender can send the bits in the group at any time, but the receiver never know when they will arrive. A common example is the communication with the host computer keyboard. Press a letter key, numeric keys,
prada handbags, or special character key to send an 8-bit-bit ASCII code. Keyboard send the code at any time, depending on the user's input speed, the internal hardware must be able to type at any time to receive a character.
asynchronous transfer there is a potential problem, namely, the receiver does not know when data will arrive. It detects the data and respond to before the first bit is over. It's like someone unexpected came up from behind to talk to you, and you had time to react, the missed the front of the words. Therefore, asynchronous transfer of information each with a start bit at the beginning, it notifies the receiver data has been reached, which responding to the receiver, receiver and cache data bit of the time; in the transmission end, a stop bit that the termination of the sub-transmission of information. By convention, idle (no transmission of data) line carrying a representative of the actual binary 1 signal, the start bit asynchronous transfer the signal to 0, the other bits to transmit the data signal with the change. Finally, the stop bit to signal to re-change back to 1,
mulberry handbags, the signal is maintained until the next start bit arrives. For example, the keyboard on the number
implementation of asynchronous transfer easier, as each information with a In the above example, more than every 8 bits to transmit two bits, the total transmission load to increase by 25%. For a small amount of low-speed data transmission equipment, not be a problem, but for those very high-speed data transfer devices, 25% of the load added to quite serious. Therefore, commonly used in low-speed asynchronous transfer equipment.
to write to the disk if
, asynchronous is to write Buffer,
Men should live like the wolf - Qzone log, and then write the destination disk, such as the original written 12,345, and the target-side write only 1. Synchronization is not received will receive a written ranging from the local disk, making it easy Buffer obstruction. Synchronous transmission is usually much faster than asynchronous transmission. Receiver do not have to start and stop of each character for the operation. Once the frame synchronization character is detected, it will arrive in the next data receive them. In addition, the simultaneous transmission of the overhead is relatively small
2. synchronous transmission (Synchronous Transmission): synchronous transmission bit grouping is much greater. It is not independent transmission of each character, each character has its own start and stop bits,
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the first part contains a set of data frame synchronization character, it is a unique combination of bits,
louis vuitton denim, similar to the previously mentioned start bit, used to notify the receiver of a frame has been reached,
一个12岁小女孩正在家做爱，被妈妈发现后。。。。。。, but it also can ensure that the receiver The sampling rate and bit rate consistent with the arrival,
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frame is a frame the last part of the closing tag. And synchronization character, as it is a unique string of bits, similar to the previously mentioned stop bits, used to indicate no other before the start of the next frame will arrive in the data.
synchronous transmission is usually much faster than asynchronous transmission. Receiver do not have to start and stop of each character for the operation. Once the frame synchronization character is detected, it will arrive in the next data receive them. In addition, the simultaneous transmission of the overhead is relatively small. For example, a typical frame may be 500 bytes (ie 4000 bits) of data, which may contain only 100 bits of overhead. At this time, the increase in bits so that the total number of bits transmitted increased by 2.5%, which is 25% of asynchronous transfer of value-added is much smaller. With the actual data in the data frame bits increases, the percentage of overhead bits will be reduced accordingly. However, the longer the data bits, the buffer cache data the greater the need, which limits the size of a frame. In addition, the larger the frame, which occupies a continuous media transmission time is longer. In extreme cases, this will cause other users to wait too long.
Triggered along a kind of eating bread
Linear Mode
