DATA TRANSMISSION SYSTEM WITH LINK ACCESS PROTOCOL CONTROLLER AND MODEM

摘要

The controller interposes between an ordinary modem and a CPU to reduce the load of the CPU. The CPU (1) enables three-state buffers (12,13) via PIO (11) in order to communicate the other terminals in the command mode. A bult-in controller (6) produces dialing pulses and detects carrier signals to inform the CPU of the time to communicate. The CPU then disables buffers (12,13) and enables three state buffers (7,8) connected to the controller (6) and the buffer (10) connected to the modem (9) in the communication mode.