Similarly, the background task expects input from the controlling terminal, but the controlling terminal has no way of directing any characters you type to the stdin of a background process.
When you run a job in the background with default bash terminal settings, bash normally catches SIGCHLD signals and prints a message after the next terminal output line is printed.
This paper introduces the development background of network audio playing terminal based on DS80C400, and expounds the system function requirements and the design of software and hardware.