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Lesson 3.9 Types of Handshake
Data transfer conditional and without condition
Handshake
By studying the lesson you will
know how to move data between devices
Knowing the role of the handshaking signals
3.9.1 Data transfer conditional and without condition
The processor communicates with the input-output units via the data path. The data transfer can be done either without conditions or with the Treaty.
In a data transfer without condition is not guaranteed and do not know if this transfer was made. For example this may occur when the processor sends an input into a regional facility without knowing whether she would accept it. The data, which emits a processor in such a way, it usually orders the regional unit for its control. Also, data transfer without condition we have from a peripheral unit to a processor when it wants to inform the editor of her condition.
Data transfers are generally made without condition only when we know that no data will be lost and do not need synchronization signals.
Example data transfer without condition is the data transfer from the processor to a display. In this case, the processor assumes that the display is ready to receive data and does not confirm the receipt.
The data transfer condition, the execution of the command data transfer requires that the peripheral device is ready to receive or send data. For information on the status of peripheral device used special marks. These signals are called handshake signals and allows the synchronization of processor and peripherals so that data is transferred correctly. Data transfer with a treaty made with the three modes
Handshake simple pulse
Simple handshake
Double Handshake
described below.
3.9.2 Types of handshake
Handshake simple pulse
The handshake uses a simple pulse control signal which declares the transfer. Usually used for slow peripheral devices. For example, a keyboard that connects to a computer system is a slow peripheral device input. When a button is pressed, then the pliktrogio sends data to processor along with a handshake signal triggered alerts the processor that has a new fact. This label indicates the new situation with a simple pulse called "strobe". (Figure 3.9.1) This kind of assumes that handshaking data transfer from the peripheral device is done slowly so that the processor can manage to take all the data without losing any. In simple handshake pulse we have confirmation that the data transfer is complete.
Figure 3.9.1 Handshake simple pulse
* The timing diagrams of digital systems change in the price of a line represented by the intersection of the lines in time when any change becomes
Simple handshake
A more complex data transfer condition is that of a simple handshake. In two simple handshake signals used for data transfer. One brand is called "Strobe" and another mark recognition (ACK). (Figure 3.9.2) When the processor, for example, wants to send data to a printer, which is an output device then gives background, along with the strobe signal notifies the printer that has sent a new fact. The processor will not send new data to the printer if the latter did not respond with the ACK signal that it received the data and that is ready to receive new. If the processor sends new order without receiving the ACK signal then you may lose data.
Figure 3.9.2 Simple handshake
Instead if we have an input device that wants to send data to the processor, the ACK signal and strobe produced instead. That is, the peripheral device generates data and STROBE signal processor and signal ACK.
Figure 3.9.3 Control signals to the simple handshake
Double handshake
Finally the double handshake is the surest way to transfer data. Again, two control signals with the names and strobe ACK (recognition). In this case the signals are used with different meanings than the simple handshake. Suppose a processor wants to send an input into a regional unit. The first thing to do is to give the positive front strobe signal asking if the peripheral unit is ready to receive data. (Figure 3.9.4) The processor does nothing if you do not get a response from the peripheral unit that is ready. This turning in front of the positive pulse signal ACK replies that it is ready. When the processor receiving the data gives the answer and also gives a negative signal front strobe. Thus, the peripheral unit understands that it has valid data in rows and reads the value given. Once the regional unit reads the data then gives the negative front ACK signal notifying the CPU to read it.
Figure 3.9.4 Double Handshake
What did you learn
Data is transferred between units without a treaty and a treaty.
The transfer of a treaty made with a simple handshake pulse, single and double handshake.
The data transfer control signals used condition which we call the handshake signals (strobe and ACK).
Terminology
Handshake simple pulse
Simple and double handshake
Transfer without treaty and a treaty
Control knowledge
What types of data transfer condition exist?
What are the control signals in a simple handshake?
How is a data transfer to the double handshake?
