Process Settings

There are a number of default settings established for each process on the system. These settings define the state of the type-ahead buffer and provide or deny user access to the TCL stack and the Debugger. The default settings are shown in the table below, along with the command used to change each setting.

Setting	Default	Command
Type-Ahead Buffer	ON	TA-ON/TA-OFF
Type-Ahead Wrap	OFF	PROTOCOL
Type-Ahead Bell	ON	PROTOCOL
TCL Stack	ON	STACK-ON/STACK-OFF
Debugger	ON	DEBUG-ON/DEBUG-OFF

Note that the default settings may be different on your system. For instance, end-user applications usually disable the BREAK key, denying users access to the Debugger.

The Type-Ahead Buffer

Each process maintains a type-ahead buffer that stores up to 127 characters. The type-ahead buffer allows a user to continue typing another command while the system is still processing a previous command. In other words, the user does not have to wait for the TCL prompt to reappear to begin typing. User input is collected in the type-ahead buffer and processed when the system is ready for it.

After a coldstart, the type-ahead buffer is on for all processes. The LIST-LINE-CHARS (LLC) report shows whether or not the type-ahead buffer is on or off and how many characters are in the buffer. The type-ahead buffer can be disabled by the TA-OFF command and enabled by the TA-ON command.

In addition, the PROTOCOL command has several options that affect the operation of the type-ahead buffer:

wrap	Type-ahead wrap is normally disabled (-W) so that the type-ahead buffer will not accept input after 127 characters. If type-ahead wrap is enabled (W), the type-ahead buffer will continue to accept characters once the buffer exceeds 127 characters. The additional input pushes out characters from the beginning of the buffer.
bell	A bell signal is sent whenever the type-ahead buffer is full. If the bell is disabled (-B), no signal is sent.
clear	When the C option is specified, the contents of the type-ahead buffer are cleared.