7526 DCT Reference

Buffered Mode

Buffered mode allows the terminal to place all transactions in the transaction queue as they are entered. The terminal controller poll retrieves the transactions in first-in/first-out (FIFO) order as they have been placed in the transaction queue. The transaction is removed from the queue upon receipt of an ACK from the terminal controller.

If the terminal controller is not polling the terminal, new transactions continue to accumulate in the transaction queue.

The operator may continue entering transactions until the BUFFER FULL message is displayed on the terminal's screen. Then, the terminal controller must poll some of the transactions from the terminal before new transactions can be entered.

Chapter 5. Communications Control Protocol 1283

This chapter specifies the communications control protocol used by the 7526 DCT and outlines the requirements for control command structures, control characters, and communications symbols.

The IBM-designed 1283 communication line control protocol is the basis for communication between the terminal controller and the attached 7526 DCT. The protocol uses ASCII characters for communication between the terminal controller and various terminals, including the 7526 DCT. The data link may be either a polled, asynchronous serial connection or a non-polled Ethernet connection using TCP/IP UDP datagram sockets.