EXOS 2.1 Editor Driver Specification

4. Writing to the Editor

Any characters in the range 20h to 9Fh, written to the editor are regarded as printing characters and are put into the text buffer at the current cursor posistion and displayed on the video page. They are subject to word wrap as described above.

The editor will also interpret the following control codes. All codes in the range 00h to 1Fh not mentioned here are ignored.

00h (NUL) - Writes a null to video to check it is still OK.
09h (TAB) - Move to, or insert spaces to, next tab stop.
0Ah (LF) - Ignored.
0Dh (CR) - Goes to start of new line (equivalent to CR-LF).
18h (^X) - Set left margin at cursor column.
19h (^Y) - Clear to end of line.
1Ah (^Z) - Clear whole buffer and screen and home cursor.
1Bh (ESC) - Starts escape sequence (see below)

The only escape sequence interpreted by the editor is to position the cursor at arbitrary co­ordinates. This is identical to the video driver escape sequence for this function and details can be found in the video driver specification. It positions the cursor at the specified co­ordinates of the video page, regardless of which portion of the editor's buffer is currently being displayed.

Codes in the range 0Ah to 0FFh are interpreted exactly as if they had been received from the keyboard. These provide various editing functions and cursor movement. They are described in detail in the section on editing functions.

Next Chapter: Reading from the Editor.

David Bouman. (dsbouma@cs.vu.nl)