The TA function returns the number of characters in the type-ahead buffer for the current process, or for any other line.
Format
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TA(expr) |
Parameter(s)
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expr |
An expression evaluating to the line number of the process to be checked. If expr evaluates to any negative number, the number of characters in the type-ahead buffer for the line linked to that process is returned. If expr evaluates to a number greater than the allowable maximum number of users, -1 is returned to indicate an error. |
Description
When the type-ahead feature is on for a terminal, the TA function returns the number of characters in the type-ahead buffer. The type-ahead buffer holds a maximum of 127 characters at a time. If the type-ahead feature is off, the TA function returns 0.
To toggle the type-ahead feature on and off for the current process, the TA ON and TA OFF statements may be used. To clear the type-ahead buffer for the current process, the TA CLEAR or INPUTCLEAR statement may be used. See TA Statement for more information on controlling the type-ahead feature for the current process or for any other process.
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NOTE |
On the console port, the TA function returns a count of two characters for every character in the type-ahead buffer. The first character expresses how the character is to be displayed, and the second character is the actual character in the type-ahead buffer. |
Example
In this application, preparations are made for dialing a remote system via a modem, which is connected to a line MODEMLINE. Before sending the modem commands, the program checks the type-ahead buffer for the line, and clears the type-ahead buffer via the PROTOCOL command if it is not empty.
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EXECUTE "LINE-ATT " : MODEMLINE CHARS.IN.TA = TA(MODEMLINE) IF CHARS.IN.TA <> 0 THEN EXECUTE "PROTOCOL " : MODEMLINE : " (C)" END |
See Also