The Display Interface

The Terminal Manager's keyboard interface has been discussed above. The display interface can also be configured. Its task is to implement, for a particular terminal, those program instructions that specify display attributes. You can accomplish most desired display options by defining, in the terminal database file, the actions that terminal function codes will take. You can specify some other display options by assigning values to special keywords in the ACUCOBOL-GT runtime configuration file.

The steps listed below describe, in a simplified way, the overall process from COBOL statement to screen display:

• Function code generation
  • The COBOL program sends output to the screen. (For example, the COBOL statement might be: DISPLAY data-item HIGH.)
  • The runtime configuration file may specify an attribute for the DISPLAY keyword. (Continuing with the example, the configuration file might include this entry: COLOR-MAP High=Blue.)
  • The Terminal Manager maps the COBOL attributes to terminal function codes. (High=HI Blue=C2)
• Function code interpretation
  • The terminal database file maps the function codes to a hardware signal. (HI=\E[0;1m C2=\E[34m)
  • The Terminal Manager sends a hardware signal to the screen. (\E[0;1m \E[34m)
• Final result
  • The display function is executed. (The data item characters are displayed at high intensity in blue.)

Restricted Attribute Handling also describes the runtime configuration file options. The terminal database file function codes and values are described in The Terminal Database File.