
296 CHAPTER 6 Processes and Operating Systems
The text compression box provides a simple example of rate control problems.
A control panel on a machine provides an example of a different type of rate con-
trol problem,the asynchronous input.The control panel of the compression box
may, for example,include a compression mode button that disables or enables com-
pression, so that the input text is passed through unchanged when compression
is disabled. We certainly do not know when the user will push the compression
mode button—the button may be depressed asynchronously relative to the arrival
of characters for compression.
We do know, however, that the ...