Exchange/RJE Manual

The Pad Character

BSC Line Control

104698 Tandem Computers Incorporated C–5

The RVI Character In both the control state and the message state, the RVI (reverse interrupt) character is

a positive acknowledgment that requests the station receiving the RVI to stop

transmitting and let the station sending the RVI transmit. The RVI character always

causes a line turnaround (the station receiving the RVI transmits next).

The RVI character is transmitted as shown:

ASCII line code EBCDIC line code

SYN SYN

DLE DLE

pad pad

The EOT Character In both the control state and the message state, the EOT (end of transmission)

character causes both stations to drop synchronization. In the message state, the EOT

character indicates the end of the transmission and causes both stations to return to the

control state.

The EOT character is transmitted as shown:

ASCII line code EBCDIC line code

SYN SYN

EOT EOT

pad pad

The Pad Character In the control state, the pad character ensures synchronization on line turnaround. In

the message state, the pad character ensures that the entire block is received and that

no characters are lost due to the subsequent line turnaround.

The pad character is transmitted as shown:

ASCII Line Code EBCDIC Line Code

Leading Pad alternating bits (01010101) %H‘AA’

Trailing Pad all ones (11111111) %H‘FF’