8 Introduction
Transmit Flow Control
Likewise, the terminal will understand the Xon and Xoff requests from the host when it is transmitting data (provided the “EIA (or Aux) Xmt” is
This terminal will stop transmitting data to the host or printer when it receives an Xoff (DC3) code. If, however, the terminal needs to send a receive protocol character, it will transmit that character even if it has received an Xoff code. When the terminal stops transmitting, the data will be buffered in the transmit buffer (64 characters for the first host/printer port and 64 characters for the second host/printer port). Once the buffer is full, additional keyboard data will be lost. When an Xon (DC1) character is received, the terminal can again send data to the attached serial device.
In addition to software “transmit” flow control
For parallel printers, this terminal monitors the BUSY and ERROR signals which are sent by the printer to determine when data transmission should be stopped or resumed.