Commodore Plus 4 - Page 149

mode description
~
~
I-
IF...
THEN
:ELSE]
~
0
1
:!
3
4
normal text
high-resolution graphics
high-resolution graphics, split screen
multicolor graphics
multicolor graphics, split screen
When executed, GRAPHIC 1 -4 allocates a 10K bit-mapped area,
and the start of the BASIC text area is moved above the hi-res area.
This area remains allocated even if the user returns to TEXT mode
(GRAPHIC 0). If 1 is given in the GRAPHIC statement as the second
argument, the screen is also cleared. Executing a GRAPHIC CLR
command de-allocates the 10K bit-mapped area, and makes it avail
able once again for BASIC text and variables.
IF expression THEN then-clause I:ELSE else-clause ]
IF...THEN lets the computer analyze a BASIC expression preceded
by IF and take one of two possible courses of action. If the expression
is true, the statement following THEN is executed. This expression may
be any BASIC statement. If the expression is false, the program goes
directly to the next line, unless an ELSE clause is present. The expres
sion being evaluated may be a variable or formula, in which case it is
considered true if nonzero, and false if zero. In most cases, there is an
expression involving relational operators { = , <, >, < = , > = , <>,
AND, OR, NOT).
The ELSE clause, if present, must be in the same line as the IF-THEN
part. When an ELSE clause is present, it is executed when the THEN
clause isn't executed. In other words, the ELSE clause executes when
the IF expression is FALSE.
Then
If
Check.
XXD?
Pnnl
OK
:_' ■■
End
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