Inside the computer, the operation system(of another software module called a data communication(71))must decide which program will get control next. Each program remember, is associated(72). a particular front -end port. If a program's data have not yet reached its front - end buffer, there is no point giving that program control. Thus the data communication monitor sends its own(73)signal to the front -end devices next port is polled. Note that the(74)computer speed. The computer never has to wait for a terminal or a communication line. Instead, it is the expressive front - end processor that waits for the slower system(75)to respond.