What Is a Buffer Device?
A buffer device acts as a fast intermediate storage between two points, such as between a camera sensor and an SD card or a GPU and the display.buffer device It allows for data to be gathered and processed without blocking the system while it is waiting for disk operations to complete or the hardware interrupts to take place.
It increases application performance by allowing synchronous I/O to finish quickly, rather than blocking while the operating system waits for hardware interrupts or the disk subsystem to complete the operation.buffer device Buffering also supports copy semantics, which means that the version of data in a buffer at the time of a system call is preserved.
The buffer is often used when there is a difference in speed between the I/O device and the software that will process the data.buffer device For example, the transmission speed of a modem is much slower than that of the hard disk, so bytes coming from the modem are accumulated in a buffer until there are enough to be written to the hard disk in one operation.
There are many different kinds of buffers.buffer device Some are bounded and can only have a fixed number of messages waiting in them at any given time, while others have an infinite capacity and the sending of new data will not be blocked even if all the messages have been read.
Some buffers can change the voltage of their output by a given amount based on an input. For example, a tri-state digital buffer can turn its output from high to low or vice versa based on whether its control input is active or not. The buffer can also have inverting varieties that output the inverse of their input, which is common in digital circuits such as decoders and state machines.
Other types of buffers are more specialized. A voltage buffer amplifier takes a current with a relatively high output impedance and turns it into an ideal voltage source with a zero output impedance. Such a buffer can be very useful when a circuit needs to drive a load with a much smaller current than the source, because it prevents the second circuit from loading up the first circuit's current unacceptably and possibly damaging it.
Another kind of buffer is a memory buffer that stores data temporarily until the system has time to process it. Memory buffers can be very large, storing many megabytes or even terabytes of data. This is particularly useful for applications such as computer graphics where large image data needs to be stored before it can be rendered on a screen or displayed by a video display. This type of buffer can be implemented in RAM, which has significantly faster access times than a hard disk. Alternatively, it may be implemented as part of the hardware itself.