Atari XL - Page 60

50
The Ateri XL Handbook
Cursor Control
Just as we can use the cursor keys to move the
cursor round the screen, so can we use a program to
move it. As described in Chapter 3, the XL
interprets four characters as control codes
governing the cursor movement.
The characters can be used within strings. For
example:
10 DIM CD$(20): DIM CU$(20)
20 PRINT" "
30 PRINT "TOP LINE"
40 CD s" -It -It -It -It -It -It -It -It -It -It "
50 cus = "i iii iii iii"
60 FOR T = 0 TO 500:NEXT T
70 PRINT CDS; "MIDDLE LINE"
80 FOR T = 0 TO 500:NEXT T
90 PRINT CU$;"BACK TO THE TOP!";
CDS
prints the three messages in various parts of the
screen using the strings CD$ and CU$ to move the
cursor.
You can use the other control characters in a
similar way - to insert or lines and characters, to
set and clear tabs, and so on.
The way in which data is presented on the screen is
an important part of the program and can make the
difference between a program being easy to use, or
frustrating and confusing. Make good use of the
commands available!