NCR 7800, User Manual, Page: 73 / 112

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RS-232 Parameters - 2
Contains some of the parameters required for RS-232
communications.
Binary Check Character (BCC) is the exclusive OR of each
byte sent prior to the BCC, except for the prefix byte. The
BCC Option parameter permits you to enable or disable BCC.
When enabled, the BCC is the last character sent. Scan the
Hex 0 tag to disable the BCC Option or scan the Hex 1 tag to
enable it. The default is for BCC to be disabled.
Permits you to select how to control the transfer of data to the
host terminal or PC. The selections are: None, ACK/NAK,
XOn/XOff, and ACK/NAK and XOn/XOff.
If you select ACK/NAK, each message sent requires an ACK
or a NAK to be returned before another message can be sent.
Receiving a message properly causes an ACK to be sent. If
there are any errors, a NAK is sent instead. The message is
then sent again.
An XOff message, which can be sent at any time,
does not permit the transmission of data an XOn message is
received. If sending a message when an XOff is received, data
transmission stops after sending the current byte. After an
XOn message is received, the remainder of the message is
sent. XOff and XOn messages are not acknowledged with
ACK or NAK messages.
Select the interface control you want by scanning the
appropriate Hex 0 through Hex 3 tag. The default is None.
BCC Option
Interface Control