Multi-character Sequences for Graphics

Some terminals require more than one character in the escape sequence that draws a graphical line segment. For example, the two-character sequence \E\202 might be required to draw a single horizontal line character.

ACUCOBOL-GT permits up to three characters to be specified in an escape sequence that draws a single line segment. The three characters are stored separately and assembled into a single sequence by the Terminal Manager.

When these multiple-character sequences are used, the GO (graphics on) and GF (graphics off) codes serve special purposes. GO is used to store the first character in the sequence, and GF is used (if needed) to store the third character.

You tell the runtime system (by including the GE code) that GO should be sent to the terminal before each GM graphical character that is sent, and GF should be sent after each GM graphical character.

Also you must make sure that the GM character list contains the appropriate characters. To handle the example mentioned above, in which a horizontal line segment requires the two-character sequence \E\202, you would add two codes to the terminal database entry: :GE: and :GO=\E:, and also add \202 to the GM character list in position one (horizontal line character).

Some VT-100 emulators support line drawing by using alternate character sets. They turn on graphics by sending ESC(0 and turn it off by sending ESC(B. The entry is:

vt100|vt-100|DEC VT-100 :\