Terminal Management › Line Mode › Writing a Line of Data

Writing a Line of Data

To transfer data from program variable storage to the screen, issue a WRITE LINE TO TERMINAL statement. DC automatically inserts the appropriate device control characters.

Transmission of Data Stream

WRITE LINE TO TERMINAL transmits a data stream to the terminal, as follows:

• For line-by-line devices, DC writes each line to the terminal immediately after the program issues the WRITE LINE TO TERMINAL request. New lines are added to lines already on the screen until the screen becomes full or the program requests DC to begin a new page.
• For 3270-type devices, DC collects the number of output lines in buffers (or pages) that correspond to the terminal model in use. Data is written to the screen when:
  • The buffer becomes full
  • A READ LINE FROM TERMINAL request is issued
  • A WRITE LINE FROM TERMINAL request that specifies the NEWPAGE option is issued
  • The issuing task terminates

Formatting the Line

With either device type, data passed with each WRITE LINE TO TERMINAL request begins in the first character position of the next available line on the screen. If the length of the data exceeds the width of the screen, DC automatically reformats data into lines of the appropriate width.

Example of WRITE LINE TO TERMINAL

The figure below shows the processing associated with WRITE LINE TO TERMINAL requests for 3270-type terminals.

When the program issues the WRITE LINE TO TERMINAL NEWPAGE request, DC writes all buffered lines to the terminal. Because the data in line 3 exceeds the width of the screen, it is displayed as two lines.

Displaying Header Lines

If you want to display header lines that will appear on the terminal, include the HEADER option of the WRITE LINE TO TERMINAL statement. This header will be displayed until a subsequent WRITE LINE TO TERMINAL request modifies or deletes it.

You can display a maximum of three header lines; each line can be a maximum of two physical terminal lines in length. Headers are cleared at the end of each line I/O session.