Earlier, we solved the bounded buffer using two semaphores. The producer waits for space to become available, while the consumer for items to placed in the buffer. Output Driver instead of having the lower half wait for characters from the upper-half, have the upper half wait for space in the buffer. The transmitter continues until the queue has emptied. Used by emacs .
Gives input a line at a time.
For example echoing is turned off when entering a password. See Fig 5-19. Each terminal device has an associated control block that contains relevant information about the status of current activities. Typically, the system maintains an array of control blocks, indexed by minor device number. It would be easy to add code to ttycntl to handle this case.