Atari 400 Technical Reference Manual page 197

9. TEXT/GRAPHICS SCREEN
See Section 5 for a discussion of the text and graphics screens
and their Handlers.
Cursor Control
For the text screen and split-screen text window there is a
visible cursor on the screen which shows the position of the next
input or output operation. The cursor is represented by inversing
the video of/the character upon which it resides; but the cursor
can be made invisible, at the user's option. The graphics screen
always has an invisible cursor.
The cursor position is sensed by examining data base variables
and can be moved by altering those same variables; in addition,
when using the Screen Editor, there are cursor movement control
codes that can be sent as data (as explained in Section 5).
91 CRSINH [02FO,1] -- Cursor display inhibit flag
When CRSINH is zero, all outputs to the text screen will be
followed by a visible cursor <inversed character); and when
CRSINH is nonzero, no visible cursor will be generated.
CRSINH is set to zero by power-up, the [SYSTEM. RESET] or [BREAK] keys
or an OPEN command to the Display Handler or Screen Editor.
Note that altering CRSINH does not cause the visible cursor to
change states until the next output to the screen; if an
immediate change to the cursor state is desired, without altering
the screen data, follow the CRSINH change with the output of
CURSOR UP, CURSOR DOWN, or some other innocuous sequence.
92 ROWCRS [0054,1] and COLCRS [0055,2] -- Current cursor
position
RoweRS and COLCRS define the cursor location (row and column,
respectively) for the next data element to be read from or
written to the main screen segment. When in split-screen mode,
the variables TXTROW and TXTCOL define the cursor for the text
window at the bottom of the screen as explained in 84 below.
The row and column numbering start with the value zero, and
increase in increments of one to the number of rows or columns minus
1; with the upper left corner of the screen being the origin
(0,0).
ROWCRS is a single-byte variable with a maximum allowable value
of 191 (screen modes 8-11); COLCRS is a 2-byte variable with a
maximum allowable value of 319 (screen mode
8).
OPERATING SYSTEM C016555 -- Appendix L
212